At least in Firefox this doesn't appear to be true, at least not always. Recently I noticed that on my main PC, if I have uBlock Origin enabled, all network re

At least in Firefox this doesn't appear to be true, at least not always. Recently I noticed that on my main PC, if I have uBlock Origin enabled, all network requests are delayed significantly. So I made a bug report on uBlock Origin's Github. They couldn't find the issue and they eventually asked if I could try it with another ad-blocking addon, and sure enough, the same bug. So the issue was with Firefox, not a specific addon. So I made a performance profile and made a Firefox bug report. It took some time but they eventually figured that it was because I run a 240Hz monitor, which was causing some events not to fire until a timeout expires: https://bugzilla.mozilla.org/show_bug.cgi?id=1684703 https://bugzilla.mozilla.org/show_bug.cgi?id=1684703.