Performance regression Nov 12

[jonnor]

Likely this is from when we updated to BABL 0.1.20 (from 0.1.18) / GEGL 0.3.10 (from 0.3.6).

[jonnor]

The distribution of processing time has changed. It has stretched out considerably, which explains percentiles increasing and average shifting upwards. It is also become bimodal instead of the nicely uniform distribution of before.

[jonnor]

Average processing time went from 2.97 seconds to 4.5 seconds, a +50% increase.

[jonnor]

More worrysome is that 90% percentile is up to 8 seconds from 4.5 seconds. This significantly impacts our ability to guarantee timely delivery in all cases.

[jonnor]

Images which were downscaled a lot were over twice as slow, images which was not downscaled a lot were ctually a little bit faster.

[jonnor]

Also for big images which were not downscaled so much shows much smaller change. This supports @hodefoting theory that this is mostly about the improved downscaling, which now takes more input pixels into account.