For averyone wondering why converser.eu is slow and/or you can't register, I had a conversation with the admin of matrix instance converser.eu, the convo is in french so i'm copying the translation here ! (I did remove my and someone else's answers so you only have their explanations)
"- FYI, I'm the admin of the converser.eu server. I know that right now, the server is a disaster. I'm doing my best. Synapse is a pain to administer and optimize. We have almost 7,000 accounts on the server and that number is still growing. We could greatly improve the situation by switching back to a server with SSD. I had to switch back to HDD because of disk space, which obviously doesn't help performance. But I'm stuck because of budget constraints. However, if you feel like it, you can help: https:// liberapay.com/converser.eu/ . "
"- It's been eight years since I launched the server, paying for successive servers to maintain the service. I've spent hours trying to understand performance issues when they arise, getting everything back up and running. In short, I'm doing my best."
"- Thank you for your support. I admit that I am very, very bad at communicating. And ultimately, when I launched the server eight years ago, I didn't think it would take on such proportions. As for closing registrations, it's complicated. Shutting the door when people need it or want to try it out could clearly discourage them from switching. And the converser.eu server is known for being open and hosted/managed in France. If I suddenly close registrations, I'll have to deal with all the emails asking me “why can't I register?”