Fix performance issues

[Frando]

There's lot to optimize for sure but in general it runs fine already, but sometimes iroh-live (with iroh-live-gpui) starts to max out my CPU, bringing my laptop to a halt.

Here's a profile:

laptop-dead.json

Download and open in https://profiler.firefox.com/

[Frando]

I think it is fixed, but leaving the issue open for a bit more to check again.