Particles - This section allows you to adjust the number of particles displayed during spell effects. In some cases a lower setting may improve performance. You can make adjustments for Spells, the Environment (Env), and Player particles. You should set these for Me + NPC, and just pick a low density if you are using a slow computer. A lot of AE spells have particle effects that flood the area they affect, and sometimes seeing these particles is the difference between life and death. I wouldn't use anything other than Me + NPC unless you like to see a LOT of flashy particle effects.