After updating to SL-2.6.1 the other day, every time I log in, there's a bad (4-5 second) screen freeze. The first time I logged in, there was a freeze but also a message that said something like "making updates", so I figured it was a one-time cleanup/refresh. But the freeze has been happening every time.

If you turn on the option Ad-Hoc Window Updates on the General tab, the addon will no longer refresh upon logging in. This will speed up your login time and remove the freeze. However, you'll likely encounter a small freeze when you open the main window of ATT, as the refreshing will take place then. If you then still encounter freezes upon login, you'll want to turn Automatically Open the Mini List (and any other windows) off under Features > Modules & Mini Lists.

Ah, perfect! That option must have gotten unchecked somehow when upgrading the other day. Working well now. Thanks!