I'm on jerboa, and my only posting issue is pictures taken with my phone get posted sideways.

Yes

I'm on android using jerobe or whatever it's called and posting and replying is pretty fast. When I'm on mobile web the loading takes forever it just spins. When I'm on desktop web it goes faster I think it depends

Usage is off the charts right now. A lot of stuff is a big sluggish. I wouldn't sweat it, it will likely improve in coming days as admins get better at tuning stuff and devs get some performances fixes in the codebase.

Instances are overloaded, if you want to help out switch to using a smaller instance.

This is due to the server status most likely. Lemmy went from around 8000 users to about 75,000 within a few days of Reddit's recent API changes announcement. We've gained another 10,000 users since I checked last night, and the number continues to rise.

Each website in the lemmy fediverse whether it be lemmy.ml, lemmy.world, beehaw.com, they are all hosted by the creator of the "instance" (website) not by some large company. So when a huge amount of people join a single instance, the servers for that instance start to slow down and run out of space, they require upgrades to handle the amount of users.

The neat part is, you can use any instance, we can sign up for the ones with less users to help the larger instances that are overloaded, but you'll see all the same communities and therefore content, because they're interconnected. Spreads out the load on the server to multiple servers, all across the world.