How to measure speed improvements across revisions over time?

[Martin v. Loewis]

Matthew Wilson wrote:
> I know how to use timeit and/or profile to measure the current run-time
> cost of some code.
> 
> I want to record the time used by some original implementation, then
> after I rewrite it, I want to find out if I made stuff faster or slower,
> and by how much.
> 
> Other than me writing down numbers on a piece of paper on my desk, does
> some tool that does this already exist?

I recommend to use rrd. This can record time series, and then generate
diagrams.

Regards,
Martin