have you reduced the graphics settings and put damage to "display on screen" versus in text? Also, have you applied filters to your chat log? These settings can cause the client-side to lag, and considering you've said your PC "isn't the greatest" im leaning towards a client-side problem.

As Zerich said, I'm having a much fasther, smoother operation with macros running cleaner... so it seems like this update just pushed your PC to slightly-beyond its limits...