Why do I keep getting lag spikes in Minecraft even with great specs?

Processor: AMD FX 6 Core Processor
10 GB RAM
64bit OS
Windows 8

I have Zan's minimap installed, Optifine, Millenaire and Treecapitator mods installed. I used to never have a problem with lag and lag spikes but whenever Zan's minimap loads a new layer of the world as in displaying it on the minimap, i have a huge lag spike and freeze for about 3 seconds. This never happened before but now it is. I've done a defrag, i set its priority to realtime, I lowered the priority of programs I'm not using and i even started playing it on the fastest graphics for the first time ever.

Possibly issues with one of the mods then, try to see what mod it is and use their support forum or whatever with your issues.