Firefox not rendering pages correctly, very slow after turning off hardware acceleration
While dealing with a minor issue in Firefox (videos on the Linux Foundation website weren't showing up) I came across the advice to deactivate hardware acceleration in FF. I tried it, and not only did it not fix my issue, it completely broke something that appears to affect some aspect of the appearance of EVERY website, no exceptions. If you compare the two attached images you can see how the Facebook landing page is missing some styling (first image is from FF, second from Safari, which is working normally). This is typical: most sites not consist of borders, text, and images, but styling such as colors and shading is missing.
I've cleared the cache and cookies, refreshed FF, run in troubleshooting mode, deleted FF and all Library and Application Support files and then downloaded a fresh version of FF, updated macOS, turned off firewalls and VPNs, and done many restarts… nothing seems to help. The problem persists in privacy mode and troubleshooting mode, and even in freshly downloaded FF. Maybe some underlying process that FF uses is broken?
I should also mention that loading many sites (Reddit, StackOverflow, etc.) is now extreeeemely slow. This also only happened after deactivating hardware acceleration, so I assume the issues are related.
I'm on an M1 Pro with 11.5.2. and currently attempting to use FF 91.0 (64-Bit).
Chosen solution
This could be a problem with High Contrast Mode on Mac.
See "New" in the release notes.
Firefox now automatically enables High Contrast Mode when "Increase Contrast" is checked on MacOS in the Accessibility settings.
Make sure you allow pages to choose their own colors.
- Settings -> General: Fonts & Colors -> Colors: "Override the colors specified by the page with my selections above"
Try "Never" if the default "Only with High Contrast themes" isn't working.
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Chosen Solution
This could be a problem with High Contrast Mode on Mac.
See "New" in the release notes.
Firefox now automatically enables High Contrast Mode when "Increase Contrast" is checked on MacOS in the Accessibility settings.
Make sure you allow pages to choose their own colors.
- Settings -> General: Fonts & Colors -> Colors: "Override the colors specified by the page with my selections above"
Try "Never" if the default "Only with High Contrast themes" isn't working.
cor-el's suggestion fixes the issue. Thank you! By toggling the contrast in System Preferences I can see the change in real time. After turning off hardware acceleration I restarted FF, which likely let FF do an update, which is why it looked this change caused the issue. Another lesson that correlation ≠ causation! The performance issues I observed may also have been a coincidence, maybe due to some network slowness, as everything seems to be a-ok now.
The FF developers might be interested in the fact that the high-contrast mode in FF makes some text in FF preferences unreadable. Specifically, the text under "better protection against activity tracking" turns into white blocks. The attached image illustrates what I'm talking about.
