I use Liftoff and it loads most GIFs and videos. The main issue I have with it is that it cannot do full screen, but I hope they add the feature soon. It's still in an early development stage

I like Connect.

Sync seems to work quite well!

Sync is working perfectly

Try imgur viewer from the play store in conjunction with your app of choice. It handles imgur, redgif, gifycat, catbox, etc. If you set it as default as you go through things, it works as fast as the old reddit apps did. Faster, sometimes.

It also works on some websites here and there, where you can tap a video link and it opens in the viewer. Haven't tested it on porn sites because that isn't my thing, but it does fine on similar sites that don't force you to stay in browser.

Right now, I'm not aware of any lemmy apps that handle gifs very well internally. Connect is better than most in that regard, but only if you use the internal browser which sucks for anything else lol.