Hey, pretty close! 
IMO, that’s as good as it’s going to get, because the response time of the HV power supply is on the order of a millisecond or two. Going faster smears that millisecond out over a longer distance and makes it more noticeable, slowing down crowds it into a smaller space where maybe it’ll be overlooked.
We got into some speed-vs-pretty tradeoffs in a parallel discussion:
As far as a better power supply goes, looking at the guts of three power supplies on my shelf may be instructive:
AFAICT, more expensive machines (for a given size) tend to have better components, but it’s not at all clear how much better they are, because the published specs largely gloss over their shortcomings and often omit chunks of useful information.
Basically, you gotta work within the limitations of what you have, because any improvements will be marginal, at best.