Lag Spikes in World of Warcraft?

Lately ive started getting On and Off lag spikes in WoW, eairler this morning after one got me killed in World PVP I contacted a GM. The GM helped me through several troubleshooting steps which improved my comps preformance and lowered the severity of the spikes. Later I compleatly reset my UI to Blizzard Default, WTF and Interface folders deleted, and I got no lag spikes. When I readded a few of the Addons and WTF settings for my saved addon settings I noticed a few lag spikes. I know the root problem may be my addons, but I hope not. Could anyone give me more ideas to try that could help? Along with that, can someone give me a list of Addons that demand alot to run and thus can cause problems like this? Bartender, Xperl, DBM, (Fan Updated Bosstalk), NPCscan, AtlasLoot, Titan, Prat, Recount, and Grid. All are up to date.