Pale Moon is a Windows-optimized fork of Firefox ESR, rebuilt for speed and efficiency on modern CPUs. By disabling seldom-used code paths, enabling aggressive compiler optimizations (SSE2/AVX) and keeping the classic XUL add-on ecosystem alive, it delivers noticeably faster page rendering and lower memory usage than mainstream Firefox—while retaining the security benefits of a mature Gecko base.
What makes it different
- CPU-specific builds – compiled with MSVC + Intel C++ and tuned for SSE2/AVX instruction sets; 32-bit and 64-bit installers auto-detect your processor.
- Lightweight by design – telemetry, Pocket, screenshots, Rust components and optional services are stripped out, cutting ~30 % RAM usage on typical workloads.
- Classic add-on support – full XUL/XPCOM overlay extensions still work (Tree Style Tab, Classic Theme Restorer, DownThemAll!, etc.).
- Legacy interface options – keep the traditional menu bar, status bar and square tabs without CSS hacks.
- Standards compliance – SVG, Canvas, WebGL, ES2023, BigInt, Big(U)Int64 arrays, ergonomic brand checks for JavaScript classes.
- Privacy slant – no outbound pings, no experiments, no mandatory studies; all telemetry switches default to OFF.
Recent highlights (latest stable)
| Change | Benefit |
|---|---|
Added browser.bookmarks.openInTabClosesMenu pref | Middle-click or Ctrl-click a bookmark folder → menu stays open for further picks. |
| Removed Netflix Silverlight UA override | Cleaner UA string, no legacy plugin references. |
| Canvas SVG intrinsic sizing (css-sizing-3) | Images without explicit width/height now scale correctly, reducing layout shifts. |
| Memory allocator tweaks | 5-8 % speed-up on SunSpider, lower peak working set. |
| Security patch bundle | CVE-2023-5722/5723/5724/5727 plus WebP decoder fix (CVE-2023-4863) back-ported. |
| BigInt & 64-bit typed arrays | Modern crypto and WASM code runs natively. |
Performance snapshot
On a Ryzen 5 5600X / 16 GB / Windows 11 box, loading 20 heavy news tabs:
- Pale Moon x64 32.5 : ≈ 780 MB RAM, 1.3 s avg. first paint
- Firefox 115 ESR x64 : ≈ 1.1 GB RAM, 1.5 s avg. first paint
- Chrome 119 x64 : ≈ 1.4 GB RAM, 1.6 s avg. first paint
Numbers will vary, but the leaner footprint is consistent across machines.
Who should try it
- Users on 4-8 GB laptops who want maximum browse-time per battery charge.
- Fans of legacy extensions that no longer run on Quantum Firefox.
- Anyone who prefers a classic, customisable UI without proton redesigns.
- Developers needing a Gecko-based test bed with modern JS features but minimal telemetry.
Who should skip it
- Those who rely on WebExtensions that use Manifest V3-only APIs (e.g. some password managers).
- Users who need built-in Firefox Sync, Pocket or official Android companion—Pale Moon offers its own optional Sync server.
Bottom line
Pale Moon proves you can have a contemporary, secure browsing engine without the bloat. If you yearn for the lightweight, deeply customisable Firefox of old—but still want support for today’s web standards—Pale Moon is worth a download.