Internet speed shouldn’t make that big a difference in a site like Lemmy. If you’re on mobile, consider trying an app (or a different app if you’re already using one). If PC, maybe a different browser? I use Firefox, at about 50 mbps according to www.speedtest.net - lemmy loads up nearly instantly.

Another option is to use filters instead of blocks. I don’t know of a way to do it on PC, but many mobile apps support filters. You’ll have to find the right balance of being broad enough to zap all the redundant communities, but specific enough to not zap the unrelated ones that you might be interested in seeing. IMO that’s more effort than just blocking, but if internet speed is a barrier, that would make for a good plan B.