FPS problem due to addon

Hello,
I've played on the Icecrown WOTLK server and have had no issues with my fps when not using addons. Once I started using addons (bartender, omniCC etc), after starting the client a couple of times (usually after the second or third time), my character movements become choppy and my fps randomly jumps to 128, when it is capped at 120. I have an Nvidia GTX 1080 card and my V-sync is enabled both outside and in-game, so my fps is usually capped at 120. The strange thing I realized was that my fps could be at 120, but the character movements would look choppy. Deleting the addons or deleting the cache folder seems to temporarily fix the problem, but it retuns after a while when installing the addons. It could of course be the case that not all addons are causing this issue and just one or several of them are affecting the client somehow. Could also be the interplay between the clients graphics and GPU settings, in relation to the addons.

Any ideas for solutions?