The biggest problem with lemmy and decentralization right now is that for optimal performance you need to spread out the load relatively evenly between instances. The problem is that users tend to go where other users are (otherwise why go there) and that naturally leads to clumping on one or few instances which causes it to overload.

The way to solve it is to avoid having generic "anything goes" instances and instead have instances be focused on a specific topic. For example, have gaming instance, a personal finance/investing instance, all things home ownership and improvement instance, etc. You can have multiple communities per instance as long as they stay within the same general topic. This way users will naturally spread out by subscribing to different instances based on topics they're interested in. And that will solve the performance issue we're seeing with lemmy.world or other popular instances.