I just recently started experiencing very bad performance in chaos dungeons on my alts after getting to Stronghold Lv. 35 and researching the bonus XP for level 50, 51 etc. It’s like a slideshow and you are teleporting around everywhere. The game becomes almost unplayable.
The issue is being caused by the loot or xp notifications in the Chat window. After I removed the notifications for ‘My Loot’, ‘Party Loot’, ‘XP’, and ‘Currency’ the issue goes away.