ATT Version: DF-3.4.9 (2023-06-18) on retail.

Getting 1 second game hiccups, possibly due to index rebuilt or lookup with ATT enabled. Without ATT, no issues.

Reproduce steps: Enable ATT...

a) Swipe mouse pointer quickly over open inventory items, triggering lots of tooltips. Best caught few seconds after /rl and randomly happens afterwards once or twice a minute.
OR
b) Similar hiccup triggers if scrolling down the AH window quickly (after searching for everything) so it's a very very long list.

Disabling ATT (and no other addon config changes): no issues on either action described above.

Update: Looks to be inconsistent though slightly better a day afterwards. There seems to be some inconsistency between servers too. On spinebreaker it tends to still occasionally happen but on few others i've tested on I'm unable to reproduce reliably. Still occasional spike but it's random. ATT is using 350 mb of memory according to the blizzard UI.

Thanks for the report.
I'm attempting to resolve these performance issues for next release of ATT. However in the meantime see if disabling this setting improves your tooltips

Thank you! I've disabled the option. I don't know if it's 100% better but it does seem to help a lot. There's still a solid number of mini spikes where it seemingly calculates something the first time tooltip happens, but perhaps it doesn't redo the math as those subside afterwards and performance in my very limited testing is smooth. It's kind of late and I am not able to test further.

It triggers a hiccup almost every time I mouse over a several crafting items (filled crafting materials bag for miner/herbalist) in a row with that option enabled; which is likely why it didn't trigger consistently on other servers as i didn't have any crafting items there.

DF-3.4.10 release resolves the problem. Yay!