I am running AD 2.2.1 on a M1 iPad Pro - Developer Beta 17.1 RC (the same issue was present pre beta)
I also have the same lag issue and hope my input helps pin down the problem.
I have 265 fonts loaded direct from Adobe Creative Cloud into iPadOS settings and this doesn’t cause any lag at all of which can be seen in the screenshot. The problem seems to start when I load fonts direct into the AD software straight from iCloud and these comprise of free and purchased fonts from various sites. I have found that I can have approx one hundred of these fonts loaded and I don’t suffer any lag in the font picker but then when I have loaded more, approx 150+ fonts from iCloud that’s when the lag seems to start. If I delete all fonts in the AD software then solely use the fonts that are loaded into iPadOS settings from Adobe Creative Cloud the problem goes away but on the downside to that I have also found that the fonts loaded through Adobe Creative Cloud straight into the iPadOS settings page don’t initially work, When you select one of the fonts in AD they will show as a default font and the text name in the font selector will be red. If you leave the text selected then close out of the software with a swipe up then re-open and re select the font that didn’t show it will now be okay. This obviously is a pain as the same has to be done to any font that has been loaded that way to get them to work. I have added a screen shot of this issue and during that you will see no lag when I use 265 fonts from the iPadOS, the issue seems to happen when loading fonts direct in to the AD software.
I use the iPad either standalone, mounted to a Magic Keyboard and an Apple Pencil 2 and the issue happens in any combination.
Hope this helps?
RPReplay_Final1698070693.mp4