I’m not sure, I have 2 characters doing STV at the moment with tons of quests available and don’t notice any slow down.
Can you test with only Dugi enabled.
I face the same issue, using an Addon for LUA Errors called: Swatter, it gives me this error message:
Date: 2019-12-26 16:33:11
I think the error is unrelated but we can fix this one