diff --git a/README.md b/README.md
index 0ec61c0..b1cca17 100644
--- a/README.md
+++ b/README.md
@@ -234,6 +234,12 @@ Remove-Item Env:WGPU_BACKEND                     # restore the default for later
 An explicit `gl` override can bring the driver crash back on affected systems. The macOS, Linux
 and web backend defaults are unchanged.
 
+**If the app is slow on an older Windows PC:** when DirectX 12 finds no graphics card with a
+driver for it (for example Intel 4th-generation graphics on Windows 11), it only offers Microsoft's
+software renderer, which draws every frame on the processor. In that case WordCraft uses OpenGL
+instead, without setting anything. The log file records the choice (lines starting with
+`graphics:`). `WGPU_BACKEND` still overrides it, e.g. `$env:WGPU_BACKEND = "gl"` or `"dx12"`.
+
 ### macOS
 
 | Build | File | Notes |
diff --git a/ROADMAP.md b/ROADMAP.md
index 37c3a7c..e391b38 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -130,7 +130,7 @@ Ranked, to beta (detail and remaining milestones in [docs/roadmap.md](docs/roadm
 
 | Date | What landed |
 |---|---|
-| 2026-10-10 | Full re-measure against Word for Mac 16.113.4 and progress docs to the craftrules standard (this page, `docs/target-app-parity.md`, `gaps.md`, `roadmap.md`, `architecture.md`, format/layout/UI/hardware/localization parity; `docs/parity.md` → `docs/parity-checklist.md`). Landed the same day (~80 PRs): equations with OMML and an Equation tab (#191); Word 97-2003 `.doc` import (#145); right-to-left and Persian text (#207); Zotero integration (#189); Read Aloud player (#190); text boxes and floating objects editable (#46) and placed like Word (#136); floating tables (#137); track-changes fixes (#125, #244); typing parity with Word (#204); hidden text (#173); save prompts and AutoSave rules (#151); LaTeX import/export (#11); keytips and mini-toolbar (#43); Spanish, Ukrainian and Brazilian Portuguese interfaces; system theme (#249); Linux file dialogs no longer freeze (#246); Chinese UI font on Windows (#248); every installed font weight (#239); cell text direction (#245); Paste Special (#235), Advanced Find (#234), Column Selection (#237), Style Inspector (#236), custom table styles (#256), View gridlines (#243), zoom buttons (#232), inertial touchpad scrolling (#252), File Info fields kept (#268), ¶ in mixed-direction paragraphs (#278), Serbian interface (#250), table Height/Width boxes, AutoFit Contents and Table Properties (#44), AutoSave switch greyed out with the reason where it can't save (.md/.txt/.html, unsaved, browser) (#196, #176); v0.4.0 released |
+| 2026-10-10 | Full re-measure against Word for Mac 16.113.4 and progress docs to the craftrules standard (this page, `docs/target-app-parity.md`, `gaps.md`, `roadmap.md`, `architecture.md`, format/layout/UI/hardware/localization parity; `docs/parity.md` → `docs/parity-checklist.md`). Landed the same day (~80 PRs): equations with OMML and an Equation tab (#191); Word 97-2003 `.doc` import (#145); right-to-left and Persian text (#207); Zotero integration (#189); Read Aloud player (#190); text boxes and floating objects editable (#46) and placed like Word (#136); floating tables (#137); track-changes fixes (#125, #244); typing parity with Word (#204); hidden text (#173); save prompts and AutoSave rules (#151); LaTeX import/export (#11); keytips and mini-toolbar (#43); Spanish, Ukrainian and Brazilian Portuguese interfaces; system theme (#249); Linux file dialogs no longer freeze (#246); Chinese UI font on Windows (#248); every installed font weight (#239); cell text direction (#245); Paste Special (#235), Advanced Find (#234), Column Selection (#237), Style Inspector (#236), custom table styles (#256), View gridlines (#243), zoom buttons (#232), inertial touchpad scrolling (#252), File Info fields kept (#268), ¶ in mixed-direction paragraphs (#278), Serbian interface (#250), table Height/Width boxes, AutoFit Contents and Table Properties (#44), AutoSave switch greyed out with the reason where it can't save (.md/.txt/.html, unsaved, browser) (#196, #176), OpenGL fallback on Windows PCs without a DirectX 12 driver (#316); v0.4.0 released |
 | 2026-10-09 | Interface languages follow the system or Options (#12; zh-hans, zh-hant, ja); TOC page numbers as an updatable field (#52); rotating log file (#17); window geometry remembered (#38) |
 | 2026-10-08 | v0.2.0 and v0.3.0 released; Flatpak and AppImage auto-update (#22) |
 | 2026-10-07 | v0.1.0 released; contributor credits in About (#6) |
@@ -141,6 +141,7 @@ Ranked, to beta (detail and remaining milestones in [docs/roadmap.md](docs/roadm
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-10 | trivial | Progress log: Windows OpenGL fallback without a DirectX 12 driver (#316) |
 | 2026-10-10 | minor | Password-protected .docx (#281): files encrypted with a password (agile encryption) open and save; File › Info › Encrypt with Password |
 | 2026-10-10 | minor | Relanded clipboard pane, table styles editor, Manage Styles, Asian typography (kinsoku), Group/Ungroup and Shape Effects (#264 #263 #270 #271 #267 #280): catalog 390/431 (90.5%) |
 | 2026-10-10 | minor | Merged main: catalog 384/430 (89.3%), 431 commands; Paste Special, Advanced Find, Column Selection, Style Inspector, custom table styles, gridlines, zoom buttons, touchpad scrolling, File Info, Serbian landed; mainstream 54→55% |
diff --git a/apps/wordcraft/src/graphics.rs b/apps/wordcraft/src/graphics.rs
index ccd0c45..85aa433 100644
--- a/apps/wordcraft/src/graphics.rs
+++ b/apps/wordcraft/src/graphics.rs
@@ -1,33 +1,122 @@
 //! Windows graphics instance configuration, applied before wgpu can initialize any driver.
 
-use eframe::{NativeOptions, egui_wgpu::WgpuSetup, wgpu::Backends};
+use eframe::{
+    NativeOptions,
+    egui_wgpu::WgpuSetup,
+    wgpu::{Backends, DeviceType},
+};
 
-/// Restrict the wgpu instance to DirectX 12 unless `backend_override` (normally
-/// `Backends::from_env()`, i.e. `WGPU_BACKEND`) names other backends.
-pub fn configure(options: &mut NativeOptions, backend_override: Option<Backends>) {
+/// What the start-up probe learned about one DirectX 12 adapter.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct Dx12Adapter {
+    /// `Cpu` is WARP (Microsoft's software rasteriser): it works, but every frame is drawn on the
+    /// processor, which makes the app lag on older machines (#316).
+    pub device_type: DeviceType,
+    /// Whether the adapter offers the limits eframe will ask for when it creates the device.
+    pub meets_limits: bool,
+}
+
+/// The backends to initialize on Windows.
+///
+/// An explicit `backend_override` (normally `Backends::from_env()`, i.e. `WGPU_BACKEND`) always
+/// wins. Otherwise DirectX 12 only, as long as `dx12_adapters` (what a DirectX 12-only probe found)
+/// contains a usable hardware GPU. Without one, OpenGL is the way to the GPU: graphics chips whose
+/// driver has no DirectX 12 support (Intel 4th generation on Windows 11, #316) still have an
+/// OpenGL driver, and GL can't reach the AMD driver crash described in [`configure_backends`],
+/// because an AMD GPU with a driver shows up as a DirectX 12 adapter and keeps us on DirectX 12.
+/// When DirectX 12 offers only WARP, it stays enabled next to GL as a last resort for machines
+/// without an OpenGL driver either (virtual machines): wgpu prefers any GPU over a software
+/// adapter, so it's only picked when GL has nothing better.
+pub fn choose_backends(backend_override: Option<Backends>, dx12_adapters: &[Dx12Adapter]) -> Backends {
+    if let Some(backends) = backend_override {
+        return backends;
+    }
+    let hardware = |a: &&Dx12Adapter| a.device_type != DeviceType::Cpu;
+    if dx12_adapters.iter().filter(hardware).any(|a| a.meets_limits) {
+        Backends::DX12
+    } else if !dx12_adapters.is_empty() && !dx12_adapters.iter().any(|a| hardware(&a)) {
+        Backends::DX12 | Backends::GL
+    } else {
+        // No DirectX 12 adapter at all, or only GPUs that can't run the app: GL alone, so a
+        // DirectX 12 GPU that would fail device creation isn't picked over the OpenGL one.
+        Backends::GL
+    }
+}
+
+/// Restricts the wgpu instance eframe creates to `backends`.
+pub fn configure_backends(options: &mut NativeOptions, backends: Backends) {
     if let WgpuSetup::CreateNew(create) = &mut options.wgpu_options.wgpu_setup {
         // eframe's default includes GL. Creating that backend can crash inside AMD's
         // atio6axx.dll before adapter selection or any Rust error handling runs, so the
         // window never appears. Choosing an adapter afterwards is too late: only leaving GL
         // out of the instance avoids it. This matches the verified WGPU_BACKEND=dx12
         // workaround without mutating process environment variables.
-        create.instance_descriptor.backends = backend_override.unwrap_or(Backends::DX12);
+        create.instance_descriptor.backends = backends;
     }
 }
 
+/// Chooses the backends ([`choose_backends`]) and applies them to `options`. Without a
+/// `backend_override` this first probes DirectX 12 with a short-lived instance of its own, which
+/// is dropped before eframe creates the real one.
+#[cfg(target_os = "windows")]
+pub fn configure(options: &mut NativeOptions, backend_override: Option<Backends>) {
+    let backends = match backend_override {
+        Some(backends) => {
+            log::info!("graphics: WGPU_BACKEND override, backends {backends:?}");
+            backends
+        }
+        None => {
+            let adapters = probe_dx12(options);
+            let backends = choose_backends(None, &adapters);
+            log::info!("graphics: {} DirectX 12 adapter(s) {adapters:?}, backends {backends:?}", adapters.len());
+            backends
+        }
+    };
+    configure_backends(options, backends);
+}
+
+/// Lists the DirectX 12 adapters, checking each against the limits eframe's device descriptor
+/// will require. Empty when this build has no DirectX 12 backend.
+#[cfg(target_os = "windows")]
+fn probe_dx12(options: &NativeOptions) -> Vec<Dx12Adapter> {
+    use eframe::wgpu::{Instance, InstanceDescriptor};
+    // `Instance::new` panics when the build has no backend for the platform.
+    if !Instance::enabled_backend_features().contains(Backends::DX12) {
+        return Vec::new();
+    }
+    let WgpuSetup::CreateNew(create) = &options.wgpu_options.wgpu_setup else {
+        return Vec::new();
+    };
+    let instance = Instance::new(InstanceDescriptor { backends: Backends::DX12, ..InstanceDescriptor::new_without_display_handle() });
+    pollster::block_on(instance.enumerate_adapters(Backends::DX12))
+        .iter()
+        .map(|adapter| {
+            let info = adapter.get_info();
+            let required = (create.device_descriptor)(adapter).required_limits;
+            let meets_limits = required.check_limits(&adapter.limits());
+            log::info!("graphics: DirectX 12 adapter {:?} ({:?}, driver {:?}), limits ok: {meets_limits}", info.name, info.device_type, info.driver);
+            Dx12Adapter { device_type: info.device_type, meets_limits }
+        })
+        .collect()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
-    fn configured_backends(backend_override: Option<Backends>) -> Backends {
+    fn configured_backends(backends: Backends) -> Backends {
         let mut options = NativeOptions::default();
-        configure(&mut options, backend_override);
+        configure_backends(&mut options, backends);
         let WgpuSetup::CreateNew(create) = options.wgpu_options.wgpu_setup else {
             panic!("default native options must create a wgpu instance");
         };
         create.instance_descriptor.backends
     }
 
+    const fn adapter(device_type: DeviceType, meets_limits: bool) -> Dx12Adapter {
+        Dx12Adapter { device_type, meets_limits }
+    }
+
     #[test]
     fn windows_default_initializes_only_dx12() {
         // eframe's own default (PRIMARY | GL) would initialize OpenGL as well.
@@ -35,13 +124,32 @@ mod tests {
             panic!("default native options must create a wgpu instance");
         };
         assert!(eframe_default.instance_descriptor.backends.contains(Backends::GL));
-        assert_eq!(configured_backends(None), Backends::DX12);
+        let gpu = [adapter(DeviceType::IntegratedGpu, true)];
+        assert_eq!(configured_backends(choose_backends(None, &gpu)), Backends::DX12);
     }
 
     #[test]
     fn explicit_backend_override_is_preserved() {
+        let warp_only = [adapter(DeviceType::Cpu, true)];
         for backends in [Backends::VULKAN, Backends::GL, Backends::DX12, Backends::VULKAN | Backends::DX12, Backends::empty()] {
-            assert_eq!(configured_backends(Some(backends)), backends);
+            // Whatever the probe would have found, the override wins (the probe doesn't run then).
+            assert_eq!(choose_backends(Some(backends), &[]), backends);
+            assert_eq!(choose_backends(Some(backends), &warp_only), backends);
+            assert_eq!(configured_backends(backends), backends);
         }
     }
+
+    #[test]
+    fn gl_when_dx12_has_no_usable_gpu() {
+        // #316: no DirectX 12 driver, so DirectX 12 offers only WARP (or nothing) and lags.
+        let warp_only = [adapter(DeviceType::Cpu, true)];
+        assert_eq!(choose_backends(None, &warp_only), Backends::GL | Backends::DX12);
+        assert_eq!(choose_backends(None, &[]), Backends::GL);
+        // A GPU that can't create eframe's device: GL alone, so it isn't picked over the GL one.
+        let weak_gpu = [adapter(DeviceType::IntegratedGpu, false), adapter(DeviceType::Cpu, true)];
+        assert_eq!(choose_backends(None, &weak_gpu), Backends::GL);
+        // Any usable GPU keeps DirectX 12 only, next to WARP or a weaker GPU.
+        let mixed = [adapter(DeviceType::Cpu, true), adapter(DeviceType::IntegratedGpu, false), adapter(DeviceType::DiscreteGpu, true)];
+        assert_eq!(choose_backends(None, &mixed), Backends::DX12);
+    }
 }
diff --git a/apps/wordcraft/src/main.rs b/apps/wordcraft/src/main.rs
index 15e9b4a..d825752 100644
--- a/apps/wordcraft/src/main.rs
+++ b/apps/wordcraft/src/main.rs
@@ -206,7 +206,8 @@ fn main() -> eframe::Result {
     if let Some(icon) = app_icon() {
         options.viewport = options.viewport.with_icon(icon);
     }
-    // Before eframe creates the wgpu instance: default Windows to DirectX 12 only (see graphics.rs).
+    // Before eframe creates the wgpu instance: default Windows to DirectX 12 only, or OpenGL when
+    // DirectX 12 has no GPU driver (see graphics.rs).
     #[cfg(target_os = "windows")]
     graphics::configure(&mut options, eframe::wgpu::Backends::from_env());
     let restored = saved_window();
diff --git a/docs/gaps.md b/docs/gaps.md
index 5f2a56c..fa86a4a 100644
--- a/docs/gaps.md
+++ b/docs/gaps.md
@@ -13,7 +13,7 @@ first (`gh pr list`), and update this file and the parity doc when a gap closes.
 |---|---|---|---|---|---|---|
 | 1 | **DOCX never tested on real-world files.** No corpus of files from Word, Google Docs, LibreOffice and Pages has been opened, rendered and round-tripped and compared with Word page by page | B | No corpus in the repo; `crates/docx/tests` are synthetic fixtures; "DOCX fidelity corpus: not started" since 2026-10-06 | Everyone: the files people receive are the files that break | 30–50 | [file-format-parity.md](file-format-parity.md) |
 | 2 | **Charts, SmartArt, OLE objects, ink and group shapes are dropped on open and lost on save, silently** | B | No `c:chart`, `dgm`, `wpg`, `w:object` handling in `crates/docx` | Business and academic documents lose content without warning | 10–15 to preserve and show fallback pictures; 45–70 to render and edit charts and SmartArt | [file-format-parity.md](file-format-parity.md) |
-| 3 | **Crashes and freezes in the field**: startup crash on Intel UHD Graphics (#170), freezes (#77, #59 Thai fonts, #31 font selector), no writes without admin on Windows 11 (#218), broken shape tool (#142), images can't be moved (#82) | B | 62 open issues, ~15 of them crashes, hangs or data-path failures | Anyone hit loses work or trust; the never-crash standard covers panics, not hangs or GPU driver faults | 20–30 | [target-app-parity.md](target-app-parity.md) (Stability) |
+| 3 | **Crashes and freezes in the field**: startup crash on Intel UHD Graphics (#170) (lag on GPUs without a DirectX 12 driver fixed, #316), freezes (#77, #59 Thai fonts, #31 font selector), no writes without admin on Windows 11 (#218), broken shape tool (#142), images can't be moved (#82) | B | 62 open issues, ~15 of them crashes, hangs or data-path failures | Anyone hit loses work or trust; the never-crash standard covers panics, not hangs or GPU driver faults | 20–30 | [target-app-parity.md](target-app-parity.md) (Stability) |
 | 4 | **Pagination differs from Word**: Aptos has no metric-matched substitute; columns don't balance; long footnotes don't continue; legacy compatibility options ignored; no page-by-page comparison harness | B | [layout-parity.md](layout-parity.md); [typing-parity.md](typing-parity.md) Known gaps | Page counts and line breaks differ, which matters for forms, legal and academic work | 30–50 + owner (font) | [layout-parity.md](layout-parity.md) |
 | 5 | **Formatting revisions, move tracking and content controls** are lost (`w:rPrChange`/`w:pPrChange` absent; `w:sdt` unwrapped) | B | Issue #41; source grep | Legal and editorial review workflows; templates with form controls | 12–18 | [file-format-parity.md](file-format-parity.md) |
 | 6 | **No native printing** on desktop: File › Print opens the PDF in the system viewer, which prints (#286); no print dialog of our own (printer, copies, ranges); web prints through the browser (#209) | B | `ui.print` → `apps/wordcraft/src/print.rs`; issue #15 | Everyone who prints | 5–8 | [hardware-parity.md](hardware-parity.md) |
@@ -64,6 +64,7 @@ The same gaps grouped the way the parity documents are, for agents working in on
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-10 | trivial | #3: Windows lag on GPUs without a DirectX 12 driver fixed with an OpenGL fallback (#316) |
 | 2026-10-10 | trivial | #6: desktop File › Print opens the system PDF viewer (#286) |
 | 2026-10-10 | trivial | Table Properties dialog landed (#44); removed from the dialog-depth list |
 | 2026-10-10 | trivial | Merged main: landed features removed from the feature-gap list |
diff --git a/docs/hardware-parity.md b/docs/hardware-parity.md
index f9a3934..ebcfb96 100644
--- a/docs/hardware-parity.md
+++ b/docs/hardware-parity.md
@@ -11,7 +11,7 @@ pens, microphones (Dictate) and speakers (Read Aloud), and displays.
 | Hardware | Word | WordCraft macOS | Windows | Linux / BSD | Web | Parity | Hours |
 |---|---|---|---|---|---|---|---|
 | Printers: native print dialog, printer choice, copies, duplex, page ranges, tray, scaling | ✅ (`WordPDE.plugin` print-dialog extension on Mac) | 🟡 PDF opens in Preview to print (#286) | 🟡 PDF opens in the default viewer (#286) | 🟡 PDF opens in the default viewer (#286) | ✅ browser print dialog (#209) | 35% | 5–8 |
-| GPU rendering, HiDPI/Retina, pixel-aligned text | ✅ | ✅ wgpu + vello_cpu rasteriser, whole-pixel text (#110, #165) | ✅ DirectX 12 default (#50); startup crash on Intel UHD (#170) | ✅ (soft text on KDE at some zooms, #140) | ✅ | 80% | 3–5 (bugs) |
+| GPU rendering, HiDPI/Retina, pixel-aligned text | ✅ | ✅ wgpu + vello_cpu rasteriser, whole-pixel text (#110, #165) | ✅ DirectX 12 default (#50), OpenGL when DirectX 12 has no GPU driver (#316); startup crash on Intel UHD (#170) | ✅ (soft text on KDE at some zooms, #140) | ✅ | 80% | 3–5 (bugs) |
 | Multiple monitors, per-monitor DPI, remembered window position | ✅ | ✅ (#38, #76) | ✅ (winit DPI fix pending, #155) | ✅ | — | 85% | 1 |
 | Pen / stylus: ink, pressure, eraser, ink to shape/math | ✅ (Draw tab, `InkRender.bundle`) | ❌ | ❌ | ❌ | ❌ | 0% | (Draw tab, 15–25) |
 | Microphone: Dictate | ✅ (cloud speech service) | ❌ | ❌ | ❌ | ❌ | 0% | 8–15 + owner (speech model choice) |
@@ -23,6 +23,7 @@ pens, microphones (Dictate) and speakers (Read Aloud), and displays.
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-10 | trivial | Windows falls back to OpenGL when DirectX 12 offers only the software adapter (#316) |
 | 2026-10-10 | trivial | Desktop File › Print opens the PDF in the system viewer (#286) |
 | 2026-10-10 | trivial | Inertial touchpad scrolling landed (#252) |
 | 2026-10-10 | major | First version |