The more users Mastodon's server has, the more effort and money it takes to maintain it, but it's not designed to make money, so the balance is getting worse.
Mastodon's answer is to divide it into smaller parts and manage smaller parts in order to solve the problem of large-scale services like Twitter, which are becoming too big and causing various harmful effects.
Guys, don't get discouraged if mastodon.social is slow. The solution is to move to a medium sized server that works better!
How to choose a Mastodon server
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Mastodon is designed to be a decentralized social network, and it's strengths come when it's decentralized.
I'm sure you've always thought that choosing the most well-known, popular, and popular service would be a good choice.
With Mastodon this is not necessarily the case. Rather, there are many cases where it is better to avoid such servers and choose a medium-sized server, or a smaller server, or your own server.