I think I have forgotton to post this experiment to JActionScripters.
Here is a playable demo & source code that I showed on the FITC2009 session. Storm simulation with 10000 particle.

Basically all physic and mouse interaction is calculated with bitmap force map. Precalculating mouse interaction with bitmap is much faster than doing mouse distance with 10000 particles every frame.

You can also see stupid 250000 particle version here.

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