[BETTER WAY?] analyzing variance of steps

Good afternoon

I've just coded a simple piece of code that analyzes the step between the two latest events, by subtracting them (zl stream2, unpack, subtraction, abs), that then goes to a zl stream a zl sum, and a division, to make an average of what is going on in terms of data. do you know, for an instance, a better way of archieving this, than the way I've gone thru.. I mean something more precise, and more efficient than what I've just done?

Thanks in advance
Tiago Morgado