3: Matrix.org homeserver performance should be absolutely fine now. Delays when doing things like joining big rooms are unrelated to the hardware, but perf optimisations we need to do to synapse in general. They're on the radar.
4: This is literally the first time i've heard an ask for 'copy entire message'. The other features exist in labs, and yes, we need to fix notifs and add custom emoji. "Many people asking" doesn't magically produce features unfortunately, especially when we are battling points 1 & 2. Contributions help though. Thanks for testing though.