I am currently working on a modpack with a few mods that change the terrain including Forestry, Extra Biomes XL, Natura, and Biomes O' Plenty. I think this causes lag spikes and my modpack to crash when flying around in creative. I have a decent PC and 2GB of RAM allocated to it. Does anyone know how to improve the world gen?
Optifine and Fastcraft help a LOT. Fiddle with Optifine's chunk settings in Video Settings. Make sure you're not using Forge Mod Loader's latest version, 1472. Use the recommended build instead, 1448. Optifine crashes because of the latest version's texture stitching mechanic.