I'm getting random lag as well. Not sure if it is from HB, WOW, or just my PC in general. I'm running all cleanups that I can right now.
By random lag I mean it will run fine.. then completely lag out for a second or two, then back to fine.. then lag, etc.
I tend to always set wow.exe to run "high priority" on my PC and it kind of helps sometimes.
DX123