[Nyan]

Someone made this: https://github.com/manticore-projects/fpng-java

Replacing zlib might give you a few percentage points' worth of difference, whilst fpnge would likely be several times faster.

[gred]

Very cool, thanks for the pointer! We might be able to run an internal test to check performance vs. a zlib replacement, but I think that AGPL license is going to be a showstopper for anything else...