I've downloaded the newest patch and I have just a small comment.
Maybe I am not the "prime example" of this, but the number on a dust multiplier slider does not influence the speed drastically for me. I keep it at 3.5 and it works fine (so the popping up dust multiplier of every load is not maybe necessary so much?)
The only problem I have encountered is in combination of these two things:
Accuracy mode set to
Accurate (RK4)
and an attempt of sending a
Light Pulse at that point.
It drops the framerate drastically, and starts slowing down more and more.
The particle multiplier didn't influence the slowdown.
If a Light Pulse is sent with Normal accuracy mode there is not such an issue (even though I had Dust on, Shadow on dust on, Glow on and dust multiplier set to 3.5), even if after sending out the Light Pulse the mode is moved to Accurate.
(hope this helps
and doesn't troll too much )