The UI is definitely still a work in progress. I'll keep doing a few UI improvements with each update, rather than trying to do them all at once and not having time to do anything else that update.
Auto scaling was added because people with 4k monitors couldn't read anything. I see your point about it potentially being too big though. I'll look into adding something to the Options menu so you can toggle it.
I've not had any FPS issues... Judging by your screenshots, that was on the pre-hotfix version though. I suspect the drops were caused by having too many popups open (because they didn't close), and refreshing the page would close them all, making it run fast until too many opened again.