Well, of course, when neither format is really supported, there is bound to be some problems...
What I can see in testing is that :
- In Firefox, APNG works fine, though the first time it appears it can take a short while to load
- In Chrome, SVG works fine, though the first time it appears it can take a short while to load
=> In both cases, the first thing I can improve is the preloading, which apparently still is not working properly.
- In Firefox, SVG animates... until it randomly decides not to. It's very unstable, and when it blocks, restarting the trial does not change anything - the only solution is to clear cache.
- In default Chrome, APNG does not animate since it's not supported
- In Chrome with APNG extension, APNG will animate correctly but after a short delay, because that's how the extension works : the first frame of the animation is displayed normally by chrome, then the extension detects that it's supposed to be animated and does the work, but it's not instantaneous.
Though this should not cause any flickering, since the first frame is displayed while waiting; the fade is just delayed by around 0.4s I would say.
So yeah, while there is room on improvement for preloading (I'll try to work on that), I should mention again that these formats are not supposed to be supported