Cmd-tabing to Firefox on Mac gets progressively slower

Published on in Mac

The longer Firefox is kept open, the longer it takes for Firefox to receive focus after Cmd-tabing to it. At some point it can take even about a second, which really kills the flow.

I initially thought that maybe the problem is in the AltTab app, which is an essential Mac app by they way. But nope, the problem exists even when not using AltTab.

Then I thought that maybe it's some kind of memory leak, caused/aggravated by keeping too many Firefox tabs open (a bad habit of mine). But nope, unloading tabs to free resources doesn't help either.

Only restarting Firefox helps, but that's cumbersome (takes several seconds to do :D).

Eventually I found a bug report on Bugzilla: cmd-tab back to Firefox window on macOS is slow. From a comment by Stephen A Pohl on Sep 25, 2023:

This bug is next on my list of priorities.

Yay! Now let's hope the fix is coming soon™.