[ENHANCEMENT] Performance degradation after patching #253

R4ygen commented 2026年03月29日 00:48:08 +01:00

Confirmation Checklist

• I confirm that this feature is not already present on the latest release of Phoenix. You can check what the latest version is on the Releases page.
• I confirm that this feature has NOT already been suggested on the Codeberg issue tracker, the GitLab issue tracker, and/or the GitHub issue tracker.

Please explain your proposal with as many details as necessary (Ex. what you're suggesting, why you're suggesting it, what need you thinks it will fill, who it will benefit, etc...).

Hello, I wanted to try Phoenix to harden my Firefox installation, but after patching it, I noticed Firefox was pretty sluggish and slower than usual when browsing or opening websites.

So I did a test.
I tried to benchmark Firefox before and after patching it with Phoenix and, it's indeed slower.
I've used https://browserbench.org/ for the benchmarks. The results where 8.47 for stock Firefox vs 5.31 with Phoenix. It's almost half the performance!

So I waned to ask if this is normal? Phoenix does in fact slow down Firefox this much?
Or perhaps I'm installing it, or configuring it wrong?

• I saw that there are some extended configs, but dunno what to change or if it would make a difference.
• I already had installed some extensions like ublock origin. Dunno if that could cause some conflicts making it slower.
• I'm on Windows 11. I've followed the manual installation of placing the 3 files into Firefox's installation directory and respective folders. All went well. At the time of writing, Phoenix version is 2026年02月23日.1

### Confirmation Checklist - [x] I confirm that this feature is not already present on the **latest release** of Phoenix. You can check what the latest version is on [the `Releases` page](https://codeberg.org/celenity/Phoenix/releases). - [x] I confirm that this feature has **NOT** already been suggested on [the Codeberg issue tracker](https://codeberg.org/celenity/Phoenix/issues), [the GitLab issue tracker](https://gitlab.com/celenityy/Phoenix/-/issues), **and/or** [the GitHub issue tracker](https://github.com/celenityy/Phoenix/issues). ### Please explain your proposal with as many details as necessary (Ex. what you're suggesting, why you're suggesting it, what need you thinks it will fill, who it will benefit, etc...). Hello, I wanted to try Phoenix to harden my Firefox installation, but after patching it, I noticed Firefox was pretty sluggish and slower than usual when browsing or opening websites. So I did a test. I tried to benchmark Firefox before and after patching it with Phoenix and, it's indeed slower. I've used https://browserbench.org/ for the benchmarks. The results where 8.47 for stock Firefox vs 5.31 with Phoenix. It's almost half the performance! So I waned to ask if this is normal? Phoenix does in fact slow down Firefox this much? Or perhaps I'm installing it, or configuring it wrong? - I saw that there are some extended configs, but dunno what to change or if it would make a difference. - I already had installed some extensions like ublock origin. Dunno if that could cause some conflicts making it slower. - I'm on Windows 11. I've followed the manual installation of placing the 3 files into Firefox's installation directory and respective folders. All went well. At the time of writing, Phoenix version is 2026年02月23日.1

celenity commented 2026年03月29日 04:34:54 +02:00

@R4ygen Thanks for the report - some slowdown is indeed expected, but how significant depends on your specs.

The culprit is usually due to us disabling JIT - so, at the cost of security, you can try setting javascript.options.baselinejit at your about:config to true, and restart your browser.

That should help a lot, but if it doesn't, please LMK.

@R4ygen Thanks for the report - some slowdown is indeed expected, but how significant depends on your specs. The culprit is usually due to us disabling JIT - so, at the cost of security, you can try setting `javascript.options.baselinejit` at your [`about:config`](about:config) to `true`, and restart your browser. That should help a lot, but if it doesn't, please LMK.

degausser commented 2026年03月31日 13:14:36 +02:00

fwiw, on win64/broadwell (and presumably other platforms with older/buggy drivers), media.use-remote-encoder.video [1] significantly slows down Firefox, until it fails over and generates a crash report in the profile directory; might be the culprit as well.

fwiw, on win64/broadwell (and presumably other platforms with older/buggy drivers), `media.use-remote-encoder.video` [[1]](https://codeberg.org/celenity/Phoenix/commit/68d8b01af497930a46e43247e33368729f8ae573) significantly slows down Firefox, until it fails over and generates a crash report in the profile directory; might be the culprit as well.

celenity commented 2026年03月31日 22:10:26 +02:00

@degausser wrote in #253 (comment):

fwiw, on win64/broadwell (and presumably other platforms with older/buggy drivers), media.use-remote-encoder.video [1] significantly slows down Firefox, until it fails over and generates a crash report in the profile directory; might be the culprit as well.

Thanks, will fix that for next release!

@degausser wrote in https://codeberg.org/celenity/Phoenix/issues/253#issuecomment-12472035: > fwiw, on win64/broadwell (and presumably other platforms with older/buggy drivers), `media.use-remote-encoder.video` [[1]](https://codeberg.org/celenity/Phoenix/commit/68d8b01af497930a46e43247e33368729f8ae573) significantly slows down Firefox, until it fails over and generates a crash report in the profile directory; might be the culprit as well. Thanks, will fix that for next release!

R4ygen commented 2026年04月01日 00:47:52 +02:00

@celenity wrote in #253 (comment):

@R4ygen Thanks for the report - some slowdown is indeed expected, but how significant depends on your specs.

The culprit is usually due to us disabling JIT - so, at the cost of security, you can try setting javascript.options.baselinejit at your about:config to true, and restart your browser.

That should help a lot, but if it doesn't, please LMK.

Hello! Thanks for the quick response.

So, I've redone the tests on my desktop pc (always Win 11), instead of the laptop, and in a more controlled way.

• Same benchmark site was used.
• All tests were always ran in a new private window, to have a clean environment without extensions and cookies of previous runs.
• For every test, the median of 5+ repeated tests was used (every score never fluctuated more than 0.5 anyway)
• No background programs open

The scores are:

• Phoenix stock (JIT off): 7.46
• Phoenix with JIT on: 10.50
• Zen stock (Firefox): 18.4
• Vivaldi (Chromium): 21.6

As you can see, enabling JIT does help! But we're still far from the stock performance score :<

I've included a Chromium browser to represent a baseline for the most common user, and since I come from it, I'm used to that level of "snappiness".
I went away from Firefox because of the security and performance issues but I wanted to try it back. Because in fact of customization and privacy, it's still the best platform, and I miss that.
Performance of stock Firefox are better since some years ago, but still lacks in security (especially on Android), and that's where I found this project. But if it hurts performance too much, then that's not for me sadly.

As you may have guessed, I'm not a security hardcore user. I'm mainly searching for a similar level of security and performance of Chromium, in Firefox. As many others I image. And as much as it is possible of course. For else, we'll gotta wait for Mozilla.

Afaik, disabling JIT looks like an "hardcore" option to do. Correct me if I'm wrong though.
So I was thinking: In general, what are the settings, in Phoenix, that can be disabled / enabled, to have a good balance of performance and security? The most important ones. Just to reach the needs of the common power user really, and be kinda comparable to Chromium dare I say.

Best would be to have a small description of what you would gain / loose with enabling / disabling every setting, so that every user could tweak the right profile for himself. But of course that's a fair bit of work, and many users, pretty much won't care.
So making a "base settings profile" would be a great idea imho.
I'd love to see if it's possible to harden Firefox more than the minimum amount without hurting the performance in respect to stock. Since it's already a bit behind the competition by itself.

Lemme know what you think

@celenity wrote in https://codeberg.org/celenity/Phoenix/issues/253#issuecomment-12294936: > @R4ygen Thanks for the report - some slowdown is indeed expected, but how significant depends on your specs. > > The culprit is usually due to us disabling JIT - so, at the cost of security, you can try setting `javascript.options.baselinejit` at your `about:config` to `true`, and restart your browser. > > That should help a lot, but if it doesn't, please LMK. Hello! Thanks for the quick response. So, I've redone the tests on my desktop pc (always Win 11), instead of the laptop, and in a more controlled way. - Same benchmark site was used. - All tests were always ran in a new private window, to have a clean environment without extensions and cookies of previous runs. - For every test, the median of 5+ repeated tests was used (every score never fluctuated more than 0.5 anyway) - No background programs open The scores are: - Phoenix stock (JIT off): 7.46 - Phoenix with JIT on: 10.50 - Zen stock (Firefox): 18.4 - Vivaldi (Chromium): 21.6 As you can see, enabling JIT does help! But we're still far from the stock performance score :< I've included a Chromium browser to represent a baseline for the most common user, and since I come from it, I'm used to that level of "snappiness". I went away from Firefox because of the security and performance issues but I wanted to try it back. Because in fact of customization and privacy, it's still the best platform, and I miss that. Performance of stock Firefox are better since some years ago, but still lacks in security (especially on Android), and that's where I found this project. But if it hurts performance too much, then that's not for me sadly. As you may have guessed, I'm not a security hardcore user. I'm mainly searching for a similar level of security and performance of Chromium, in Firefox. As many others I image. And as much as it is possible of course. For else, we'll gotta wait for Mozilla. Afaik, disabling JIT looks like an "hardcore" option to do. Correct me if I'm wrong though. So I was thinking: In general, what are the settings, in Phoenix, that can be disabled / enabled, to have a good balance of performance and security? The most important ones. Just to reach the needs of the common power user really, and be kinda comparable to Chromium dare I say. Best would be to have a small description of what you would gain / loose with enabling / disabling every setting, so that every user could tweak the right profile for himself. But of course that's a fair bit of work, and many users, pretty much won't care. So making a "base settings profile" would be a great idea imho. I'd love to see if it's possible to harden Firefox more than the minimum amount without hurting the performance in respect to stock. Since it's already a bit behind the competition by itself. Lemme know what you think