I think that's being worked on.
This is from almost a year back but it's still coming I believe: https://youtu.be/7yjQFmhAftE
Discussion
You can run your own simplex relay and it will be fast. But nostr already does it. So just use DMs.
The lag you're experiencing in groups doesn't depend on the relay.
It depends on the overall congestion of the network?
I don't know what you mean by "the network" in this case but it only depends on the number of group participants.
It seems to be a horrible design choice. What's the big O?
It's O(n) and yes they are aware of the limitations. It was better to get some version out quick even if it's imperfect I guess. The v2 will do it better.
There is a simplex-devs group you can join if you want to make constructive contributions. You can find it in the directory.
Thank you for a consise and informative response.
I can't even join groups because of timeouts. I'll end this comment without any scatalogical words to be nice 😁