mtpng

Are you required to use PNG or could you save the files in an alternative lossless format like TIFF [1]? If you're stuck with PNG, mtpng [2] mentioned earlier seems to be significantly faster with multithreading (>40% reduction in encoding times). If you're publishing for web, TIFF or cwebp might also be possibilities with -mt (multithreading) and -q 25 (lower compression and larger filesize but faster) flags, or an experimental GPU implementation [3]. [1] https://blender.stackexchange.com/questions/148231/what-imag... [2] https://github.com/brion/mtpng [3] https://emmaliu.info/15418-Final-Project/

I have no experience in PNG encoding, but found https://github.com/brion/mtpng The author mentions "It takes about 1.25s to save a 7680×2160 desktop screenshot PNG on this machine; 0.75s on my faster laptop." which makes me think your slower performance on smaller images either comes using the max compression setting or using hardware with worse single threaded performance. Although these don't directly solve the PNG encoding performance problem, maybe some of these ideas could help? * if users will be using the app in an environment with plenty of bandwidth and you don't mind paying for server bandwidth, could you serve up PNGs with less compression? Max compression takes 15s and saves 35MB's. If the users have 50mbit internet, then it only takes 5.6s to transmit the extra 35MB, so you could come out 10s ahead by not compressing. (yes,