bavison

If I may correct my criticism a bit (sorry, I'm a bit rusty on compositing...) Treating every colour component the same is only possible when you use what's called _premultiplied...

There are a number of benchmarks that I included with the original issue - it varies depending on the exact case, but often gave a speed-up of an order of...

LGTM. If you can easily open a PR, that'd make it simpler to ensure you get credited appropriately. I can't promise how quickly it'll filter through to the Raspberry Pi...