I question your assertion that it has 'acceptable preformance (sic)' on the grounds that you do not have an FPS meter displayed.
It's a release build, it runs smoothly on my machine (which is rather average). I'd give it at least 60 FPS, I'll have to check with a meter to be sure.
I don't want to appear rude, but those smoke trails don't look too convincing. What do you think about something like this:
As I said, I'm still working on it. Nuke's particle code allows a lot of options and I have yet to try some of them.
Also, it's an old version, Mediavps one has an updated effect, which looks better.
I've played D2X-XL and I would like to have smoke trails similar to the ones it uses. I just need some time to work on them.