I spent the afternoon on a new world and a friend's developed world, same modpack as the problem one.
No crashes It's something in my world. It's extremely frustrating.
Any time I click on something to access or modify it (click AE storage, a centrifuge, bonemeal a sapling, etc.) Is when the crashes occur. At first I thought it was because I would right click a machine with a wireless AE receiver, but then just bone-meal'ing a tree did it.
Is it possible to lag down your world by cramming a lot of items through buildcraft pipes? My multifarms, quarries, bees, crafting, everything goes into a central buildcraft/tesseract system at base that feeds into my AE drives. It sure seems that when every machine and farm is running, it generates a LOT of items to cram through one buildcraft pipe en route to the storage.