At a guess, bc it doesn't have that many communities on it?
Efforts are underway to change that but yeah it definitely lacks the same punch as others - like sh.itjust.works has 5 communities that are each larger, some by almost 3 times, than the absolute largest one on lemm.ee.
That instance seems not so much a "source" of content across the Fediverse as a "destination" for posts made to communities elsewhere.
Then again, very little else compares to Lemmy.World in that regard - it has another 10 communities each larger, some twice as large, as sh.itjust.works does. It would be healthier for the network effects to split that up a bit more... but fortunately their upgrade process over the next few months should help a little.
I'm surprised to hear about the slowness issue - I think this is the first time that I have, though I am definitely spoiled at Discuss.Online that has such a great technical admin (he also is the one who was developing Sublinks, before life and a baby intervened:-). Is lemm.ee much faster than lemmy.world for you?
Tbf there is legit fear in the USA that Trump will start to place bans or at least watchlists on social media outlets that Musk does not make money off of. Then again, I thought that LW wasn't really associated with the USA in any way besides having a bunch of users from it, and anyway you have found a perfect solution to the problem - if they don't want it, go somewhere else that does allow what you need.:-)