This is just my personal experience, but I've been focusing on playing anytime before 6 or 7 PM Eastern USA time on the US servers during the weekdays. On weekends I've been trying to get out before 3 or 4 PM Eastern. Things seem to be more stable for me then, but you can still run into some big lag spikes, and ships can borderline unusable.
After restarts, like today, things had been pretty smooth up until about 7PM EST. It's also good to check the Discord because it's more real-time there, so you'll see if people are going on about lag or not at the moment you are looking to play.
(I have toons on all the servers, but I only really log in to Moonsea for rolls at this point, so I can't really say how well performance is on that server during peak US times.)