suggestion: use the "exponentially weighted moving average" algorithm

[shogg]

It's cheaper in computation and memory use. You only need memory for the average value, not the last n values. And it's more flexible. You can specify an arbitrary large rolling window, not only the last 10 values as it is now.

I use this package for my own progressbar (not public): https://github.com/VividCortex/ewma

The README.me nicely explains the algorithm.