I have a brand new computer and started using wallpaper engine with DF. I noticed that a few hours into my day, my alt tab handler will become slow to the point where I must click the window that I want in order to access it. If I disable DF alt tab, it is fine. A restart of the computer solves this issue.

What is going on here?

I have a very similar issue to yours and I wonder if they are related.

Post sleep and wakeup in W10, DF's alt-tab takes a good 4-5 seconds to show up, and even then it is incredibly slow.

Attached log as requested. I pressed alt-tab around 11:15.00 a few times.

I will note that going into DF to enable/disable logs was very very sluggish and the app froze on multiple occasions, only to recover after. I hadn't noticed this behavior before (since I don't often find myself in the DF settings).