Yes because Tor can be very slow, the implementation in Bluewallet is not that performant, a RPi4 is slow. All that combined makes it kind of unreliable and very slow
Discussion
Hoping we make some major improvements in these areas in the coming years
Yeah, but I think the best improvements can be done by oneself already. For example: use old Laptop instead of RPi4, already much faster. Fulcrum instead of Electrs is also faster. And use clearnet instead of Tor, maybe with a VPN bridge to a VPS to preserve privacy, biggest improvement but also way more complicated to set up.