@Baertram I've had a chance to look at the areas you suggested. I also tried pChat and it works fine with no noticable hit on performance. I created an addon selector profile with all the same addons except for the two trading addons I use. It actually feels a bit more responsive. The FPS seems about the same but I have noticed the screen doesn't stutter nearly as much as before.
So a big thank you again for all your help and hard work on the addons! My next PC build should really help too, which I hope to have done by end of summer <fingers crossed>.