I don't understand why you have problems making your PID faster
the issue isn't with when the computation occurs, it's with how long the computation takes when it's excecuted. the computation fires at whatever interval the user desires (set by the SetSampleTime function) the interrupt idea is interesting. I'll have to look into that.
what I was talking about when I said "faster" was the computation itself. the fewer processor cycles it takes to perform its calculation, the more time the arduino has to do other things. and, just as a point of pride, I want the pid to be as efficient as possible.
as far as abbreviations, some are certainly more common than others, but they do vary from manufacturer to manufacturer. off the top of my head:
Process Variable: PV, ME
SetPoint: SP, SV
Controller Output: CO, CV, OUT, OT, OP.
dt is commonly used. I settled on SampleTime (which is also commonly used) because I felt it was easier to understand.
at any rate, give the library a shot! I'd love to hear any more suggestions you might have.
Brett