True. My GPU is an ATI X1600 128mb, about twice the speed of an NVidea GeForce 4 FX at only 2 billion texels/sec, compared with some of the 20-80 billion/sec at the high end, it's not exactly state of the art but is some 10-40 times slower and is roughly what you get on the lowest end iMac these days.
I'm not sure I'll have 10's of thousands of particles on the viewable screen area at once, but they will all be still moving and animating off-screen with maybe a few thousand visible at a time. But collisions and stuff still needs to happen for all objects all the time no matter where they are.
If you think about physics, in order for a physics model to be stable and continuous you have to simulate the interactions of all objects everywhere all the time, not just in some isolated local area. That means handling thousands of off-screen objects in addition to what you can see.
I'm not sure I'll have 10's of thousands of particles on the viewable screen area at once, but they will all be still moving and animating off-screen with maybe a few thousand visible at a time. But collisions and stuff still needs to happen for all objects all the time no matter where they are.
If you think about physics, in order for a physics model to be stable and continuous you have to simulate the interactions of all objects everywhere all the time, not just in some isolated local area. That means handling thousands of off-screen objects in addition to what you can see.