Two observations I've noticed since yesterday and currently still experiencing right now:
1. Much slower loading of forum pages than before generally speaking, on a Windows 10 PC using both Firefox and Brave browsers. Prior to the changes yesterday, pages consistently loaded near-instantaneously for me (other than occasional image-heavy pages in pic threads). Now sometimes it's instantaneous, and sometimes takes 2-8 seconds per load. Same can be said for site-based images/signatures. Using the underground theme at the moment, which is what I typically used before.
2. Other general forum-wide sluggishness since the changes. Before while scrolling down a large thread, you could freely and smoothly navigate down the thread, whether or not the page completed loading. Now if not completely loaded, the page freezes not allowing any movement from time to time. Even after the initial loading, scrolling up and down pages can still be a bumpy ride at times. Functions like editing a post used to be an instantaneous action, now has a 2-4 second 'hang' before it does it. Even while typing in a response can now sometimes cause hiccups.
3. Alerts can no longer be seen by instantaneously hovering over the bell icon; you now must click on the bell first, followed by a few seconds of loading. In fact, hovering doesn't seem to be functioning for anything on this forum at the moment -- at least not on my end.
Also finding the minor changes to UI a bit more clunky than before, although I'll chalk that up to a matter of taste. I'm sure things will continue to improve.