[Broken Website] hg.mozilla.org

# Broken Website Report

## Website Address
https://hg.mozilla.org/releases/mozilla-release/pushloghtml?fromchange=e695772f9f30

## Steps To Reproduce

- Set DR to use Dynamic Dark mode
- Go to https://hg.mozilla.org/releases/mozilla-release/pushloghtml?fromchange=e695772f9f30
- Scroll down using the wheel on a pointing device
- Now scroll up using the wheel
- Notice that many of the page's items are temporarily missing; I think this is likely an issue with how Mozilla is pushing the data, and not a DR issue, but I mention it in case DR can be optimized here
- Press Ctrl+F to open the Find bar
- Type in a word such as `failover` in the Find bar
- Press the `Find next occurrence` button in the Find bar
- See if the browser finds the next occurrence
- If it doesn't, that's an issue
- If it does, try pressing the `Find next occurrence` button in the Find bar again
- See if the browser actually finds the next occurrence
- At this point, sometimes I get the "An extension (Dark Reader) is slowing down the browser" message in Firefox (not the exact string, but I'm sure you've seen the message!), but sometimes it takes a little more scrolling/finding on that page for the message to appear
- I also notice that memory is getting eaten up very fast at this point (over 1GB of *additional* RAM occupied in just a minute or two)
- Finally, after using that site for a while, it takes a *loooong* time for Firefox to actually fully close and release its memory (Firefox will appear to close, but it still holds on to the memory until all its processes are completely terminated, which in this situation is unusually long). This may not be a DR issue, but I'm including it here for completeness.

## Expected Behavior
Page to load & scroll smoothly, perform Find operations quickly, and not quickly use up over a GB of RAM.

## Actual Behavior
See above

## System Information

- OS: Windows
- Browser: Firefox 92.0.1
- Dark Reader Version: 4.9.37.1

## Additional Context
I tested on a couple devices and connections. On faster devices and internet connections, this is less of an issue, and on slower devices and slower internet connections, it's more of an issue.