@schlawg Thank you very much for looking into this!
I can give you some more info relating the history with this problem, based on my own experience.
I encountered it first, probably in mid- to late August, with Brave on PC. I immediately thought it must have something to do with my system, so I cleared all browser data, tried fresh installs of Firefox, Chrome etc. I even switched to a different operating system, from Win 10 to Linux. Same issues, although I first (probably mistakenly) thought it had something to do with browsers based on Chromium (i.e. Chrome, Brave, Chromium on Linux), because Firefox seemed to be working fine at first. However, now, a couple of months later, when trying Firefox, I get the same issue, also on different devices etc. The patterns seem to be pretty consistent with the crowded server hours - I sometimes thought the problem was gone in the last few months, but that was probably because I was using the site at a different time of day, without connecting the dots.
When the issue flares up, instead of loading a page (a game page, for example), the browser window simply shows a blank screen and the process says "Waiting for
lichess1.org...". This takes then from around 10-15 seconds sometimes up to two minutes!
I hope these descriptions are helpful for closing in on the issue!