Thanks. I'm glad you enjoy it.

**Slowness**The decrease in speed isn't from drawing the particles as much as it is calculating their new velocities and positions.

**Why is it slow?**Every body with mass effects every other body in a system so a system with 10 bodies with mass requires (10x10=100) gravity calculations per step. Each particle is influenced by every body with mass: Bodies with Mass x Particles in Ring x Multiplier (10x200x20=40,000 calculations per step). Adding a single body with mass increases the calculations dramatically (11x11=121 and 11x200x20=44000). If you turn down the particle multiplier then the numbers get a lot lower (11x200x2=4400)

If you pause the simulation these calculations are not performed and the frame rate goes up.

**Short Answer**Your experience is about what I get on my development machine, so just turn the particle multiplier back down.

**Why allow such high values?**It's possible to turn up the particle multiplier higher than the fastest computers can support in real time. The high values are for fast computers in the future and non-real time movie capture.

I'm not currently supporting the Ageia PhysiX Accelerator, but is something I may look into in the future.