[dandelany]

It doesn't reload data - it just stops the particle system advection and restarts it when you're done moving.

And yes, this is pretty necessary (at least it's quite hard to work around). To maintain the same view during viewport movement, it would have to keep track of all the particle trails in lat/long space and re-project them all to the new view. But this is implemented in canvas, so the trails (ie. particle histories) are likely not stored in their entirety - more likely, the system keeps track of only the particle's current position, and the trails are accomplished by drawing new line segments over the old on each frame. Yes, it would be technically possible to keep track of each particle's full history, and to re-project them all during interaction, but it would be pretty slow.

(I didn't make this, but I've written a very similar particle system in canvas and ran into similar issues)

[bschwindHN]

I imagine you could accomplish the trails with some triangle strips in WebGL and let the GPU do the heavy lifting. I wonder if that would perform any better.