@thomasfuchs "no reason" is a bit of an over statement. For example, I'm in Canada and my server is across the ocean, so even getting the initial assets can slow things for me.
Next, these are running on community run instances that could be a laptop hard drive for all we know.
Those instances do more than just serve content, they collate, manage accounts, etc.
Those servers are running a rails app so there's some overhead built in.
That rails app is getting older and maintained by a small team.
The frontend code is starting to get archaic and has had pushback on switching to a framework like React. So fewer people can easily contribute to it.
Things like privacy and moderation tools have been a high priority for a while; performance less so. The small team's time is limited.
etc.
All of these things are solvable, but it's a problem of time and/or money. Something that is is short supply when it comes to Mastodon.