I have run into the same issue yesterday, and I have decided to test a bit what happens when each of the options is turned on or off.
The case of the simulation slowing down to less than 10 fps happens if you consider that you have a high end computer (like I did) and put the
Accuracy mode to RK4.
The
number of dust particles doesn't seem to matter. I have the dust multiplier set to 4.1 and my FPS keeps at around 47 (as long as the Accuracy mode is set to Normal at the moment of sending the light pulse - otherwise it drops to below 10fps even if multiplier is set to 0.5).
What happens than is that light pulse doesn't get shown, and the simulation just get slower and slower by each Light Pulse press. So it is calculating something obviously but it doesn't show it.
If you, however, start the light pulse with the
Accuracy mode to
Normal, you can switch to the RK4 right after the pulse has been sent out from the body, and it will continue to run normally without it dropping to 4 fps.
I hope this helps
The only problem I see now is that the tick next to
Use Multiple Processors in Advanced options doesn't seem to change anything, and it doesn't get saved after the program is shut down.
Does it actually do anything and how can that be tested?
As a reference here are a few details about the HW I have:
CPU: Core i7 860
RAM: 8GB
GPU: ATI 4770 with 512 DDR5