Large Apngs (animated Pngs) Play Slowly In Firefox

I've noticed that the smaller an APNG, the faster it plays. If it's wider than around 750px or so, or higher than around 500px, the speed becomes erratic. Fast then slow then fast then slow. And if it's really big, full HD, 1920x800 or 1920x1080, then it just plays in slow motion, like half the frame rate it should. Is there any way to fix this? Is it a browser problem, or is there a way I could optimize a large APNG so that it'll play consistently at the rate it should?

 

View the different APNG images in another program (like XnView) and see if the problem persists.

 

Large ones can be slow in XnView too, yeah. It's just my shitty, low power, low performance "computer" that's the problem, I imagine.

 

Correct.
Unfortunately large APNG images are quite resource hungry.