Just a 'lil question, what sort of plugins are you currently using? Also, I'd recommend using pTweaks and Spigot together instead of just the usual noLagg, since noLagg and Spigot don't work too well together in many ways, and an actual optimalization of CraftBukkit at its core, like Spigot is, usually offers greater performance gain than just a plugin: it's loaded before all plugins (since it's the thing said plugins hook into), and has a higher priority. Personally I've experienced a significant increase in free RAM when using pTweaks and Spigot compared to noLagg, gives you around 5% extra. Still doesn't make WorldEdit run fine though, but WE is coded in a kinda retarded manner, trying to push all block updates at once, instead of LogBlock which schedules them so the server can actually catch up and, you know.... not crash.