On my old iMac (2011) running 10.13.6 (can't run anything newer) with the last few versions of GoodTask (can't say when exactly this started, but it seems like it's getting worse). I'll switch to the app, and either get a beach ball immediately or just after I try to click or type something. Activity monitor shows 99-100% CPU and "(Not Responding)". I've tried letting it stay like this for 20-30 minutes with no change. After I force quit, a restart almost always goes straight to the same place and after another force quite I'll get a dialog that says "The last time you opened GoodTask, it was force quit while reopening windows. Do you want to try to reopen its windows again?" Once I say "Don't reopen" to that it works fine for a while.
I understand that this is an old config that probably doesn't get tested much if at all. I'm happy to collect diagnostics when it's stuck if that would help (let me know which things to do). So far I can't cause this to happen but it's happening often enough that I can safely say I'd be able to get something within a few days.