1. Firefox Private Build
1.1. Feature
These are my private builds of the Win32 version of Firefox. These builds are not the official builds of Mozilla. Personally made by me. Use it at your own risk. The features are as follows:
- Applied CSIR PGO. Create a temporary IR PGO build, then collect the profile data again with that build, and apply them to the final build. This results in optimizations that are more aligned with the actual execution of the program compared to standard IR PGO (probably).
- No installer.
- Added my patches into a Source folder.
1.2. Download
Firefox 145.0.2 private build
- x64 SSE3
-
Firefox 145.0.2 [2025112414 en-US win32 tete009 x64 sse3 cspgo] (85.3MB)
- MD5: db7675a1bc56dc7032e6d51e2901a9f0
- SHA1: 56ecf5cc82509eef8488d2a7231b75754c53ef94
- SHA256: 46a5f5672bddd4f756fc2b63904888369f6fd273ca4e069f0725f0f26b536736
Language packs:
Firefox 145.0.2 private build TEST0
- x64 SSE3
-
Custom builds of LLVM 21.1.6 and Rust 1.91.1 were used, and does not applied TeInliner.
Firefox 145.0.2 [2025112812 en-US win32 tete009 x64 sse3 cspgo] (85.3MB)
- MD5: 604832a5b8bd62b7df5c4b7eb5f364ff
- SHA1: 9e3edec162b953ad2dc75179fab0ff9bd7a6562f
- SHA256: 763e82ee211ff595289a6647bce6ffd8eede648b6c33c6c73b19f8fc83d0e047
Language packs:
Firefox 145.0.2 private build TEST1
- x64 SSE3
-
Custom builds of LLVM 21.1.6 and Rust 1.91.1 were used, and my pass plugins (including TeInliner) were loaded into and used by LLVM build tools to inline functions that meet specific conditions and thereby reduce the binary size.
Firefox 145.0.2 [2025112806 en-US win32 tete009 x64 sse3 cspgo] (85.3MB)
- MD5: e4d0bdbab75e94119fdc58fa729d84dc
- SHA1: 9a1e0fd849b6f2f8140f3dbde84aab4cab48b9c5
- SHA256: 6edb347faf6a5da140de7ce8234ed4d800495f1520bd5f5af5eac60a0f214fb8
Language packs:
Firefox 145.0.2 private build TEST2
- x64 SSE3
-
Custom builds of LLVM 21.1.6 and Rust 1.91.1 were used. Changes from TEST1: Reviewed and modified the logic of the TeInliner pass plugin.
Firefox 145.0.2 [2025113008 en-US win32 tete009 x64 sse3 cspgo] (85.4MB)
- MD5: 4efdfb80e5103bf4590f71a9debd46fc
- SHA1: 6a8c9f4747fb0c61ab4235336a1670bd9493849b
- SHA256: 86e71575cca6ff17d0900718c4ba7434a0e75d065be1b841565cbe4ba7513d05
Language packs:
Firefox 145.0.2 private build TEST3
- x64 SSE3
-
Custom builds of LLVM 21.1.6 and Rust 1.91.1 were used. Changes from TEST2: Functions that never executed and had no loops were optimized for size.
Firefox 145.0.2 [2025120308 en-US win32 tete009 x64 sse3 cspgo] (85.0MB)
- MD5: 6068f23f315b18a7b11ab0bb748519af
- SHA1: fad37d2885c4ef933d1e2e5bf6bf12bf10ccf478
- SHA256: d0d3769cddbf31bced87ba1688974934668595011b199bcd5fd038813dd91f6d
Language packs:
Firefox 145.0.2 private build TEST4
- x64 SSE3
-
Custom builds of LLVM 21.1.6 and Rust 1.91.1 were used. Changes from TEST3: Modified LLVM's MergeFunctionsPass to restrict merge candidates to infrequently executed functions, and applied the change.
Firefox 145.0.2 [2025120508 en-US win32 tete009 x64 sse3 cspgo] (84.7MB)
- MD5: 53b41dfb6ed801c42acf91bfece1cd88
- SHA1: 97ec211a4609514edbce479aded1aa5a8be3fa88
- SHA256: 786a4880d743cab2ef566ceab368cef81b36b2b36f4ddfa7b2a1b971818a2499
Language packs:
Firefox 145.0.2 private build TEST6
- x64 SSE3
-
Custom builds of LLVM 21.1.6 and Rust 1.91.1 were used. Changes from TEST4: Modified LLVM's MergeFunctionsPass to limit merge candidates to functions that are Cold and have at least 5 IR instructions, and applied the change.
Firefox 145.0.2 [2025120701 en-US win32 tete009 x64 sse3 cspgo] (84.7MB)
- MD5: 07ab1c3bcacd15dbacbee08636624f75
- SHA1: 0cd001ddd499f19aa68d8697001df85bf755adbf
- SHA256: 9d258a9fbcfb15b5600ae83072d39314931c5fd5cd9d5fed219abde3d1bd9733
Language packs:
Archives of new and old Firefox private builds
If storage space becomes low, old versions may be deleted without notice.
1.3. Benchmark Test Results
Compared scores from some benchmark tests across various Firefox-based browsers and more.
- The benchmark test was automatically executed using Selenium.
- Some browsers include extensions by default. I am looking for ways to disable these extensions as much as possible, but so far I have not found a solution. This may affect the benchmark test scores.
- PC used for benchmark testing: Windows 11 24H2, Ryzen 5 5600, GeForce GTX 750 Ti.
Speedometer 3.1 Scores

| Chrome 135.0.7049.115 | Edge 135.0.3179.98 | Tete009 137.0.2 | Firefox 137.0.2 | Zen 1.11.5b | Floorp 11.25.0 | Waterfox 6.5.6 | Mercury 129.0.2 AVX2 | |
|---|---|---|---|---|---|---|---|---|
| Score (median) | 23.8 | 22.9 | 21.0 | 20.45 | 20.0 | 18.6 | 18.5 | 14.2 |
MotionMark 1.3.1 Scores

| Edge 132.0.2957.127 | Chrome 132.0.6834.160 | Tete009 134.0.2 | Firefox 134.0.2 | Waterfox 6.5.3 | Floorp 11.22.0 | Zen 1.7.4b | LibreWolf 134.0.2-1 | |
|---|---|---|---|---|---|---|---|---|
| Score (median) | 2580.27 | 2290.30 | 1593.41 | 1487.93 | 1358.85 | 1355.76 | 1291.47 | 813.14 |
window.createImageBitmap() Resizing Performance Test Scores
| Browser | Median (ms) |
|---|---|
| Tete009 143.0.1 (AVX2パス) | 0.36 |
| Firefox 143.0.1 | 0.54 |
| Zen 1.15.5b | 0.54 |
| Floorp 11.30.0 | 0.58 |
| Mercury 129.0.2 | 0.60 |
| Waterfox 6.6.3 | 0.62 |
| Chrome 140.0.7339.186 | 0.94 |
| Edge 140.0.3485.81 | 1.10 |
1.4. How to update my builds of Firefox (my own way)
Here is my usual way of updating my builds of Firefox:
- Uncompress the self-extracting file of my build into an appropriate folder.
- Open the folder in which an old version of my build has been installed and backup the following files and folders as needed.
- searchplugins folder
- plugins folder
- tmemutil.ini file (if exists)
- folder specified by the PortableDataPath (if portable mode is enabled)
- Remove the old version of my build.
- Restore the files and folders from backup into a new version as needed.
- Change Firefox's locale setting to your locale if necessary.
- Install a language pack if necessary.
1.5. How to localize the English version of Firefox
"Firefox private build" is English version, but you can localize it in the following way:
- First, install the XPI language pack. It will be possible to get the official packages from the following URL. Replace the part of
(Firefox's version)
with the string of Firefox's version (3.0.0, etc). It is necessary to match the version of Firefox and the version of the XPI language pack:- http://releases.mozilla.org/pub/mozilla.org/firefox/releases/(Firefox's version)/win32/xpi/
- ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/(Firefox's version)/win32/xpi/
-
Next, change Firefox's locale setting to your locale. Here are three examples:
- Open or create the user.js file contained in the profile folder and add the following line.
user_pref("intl.locale.requested", "ja"); - Enter about:config in the Firefox's location bar and change the value of
intl.locale.requested
fromen-US
to your locale string. - Change the command-line string of Firefox like the following:
"~\firefox.exe" -UILocale ja
- Open or create the user.js file contained in the profile folder and add the following line.
