CAN send, yes. The highly optimized native api from esphome even needs less bandwidth than mqtt which was designed for low/limited bandwidth scenarios decades ago. I hardly expect any esphome nodes (expect the ones with camera feeds) to send even kilo or megabytes per second.
Yes, lagging of zigbee is substantial and special visible when switching to wifi (esphome) which allows real time scenarios and high update rates. Also automations literally can fail if zigbee devices have low update frequency or hard coded “cool down” timers.
Are you sure not mixing things up here? I have my microwave door usual closed when using it so no microwaves escape! Also zigbee is the known technology not only with little range but being very sensitive too and have little penetration (human body can block a weak signal completely for example). On the other hand I never had a wifi device “jumping” off my network or stop working because of microwave. Also I never thought about interference when using wifi devices - simply because it is not important - for zigbee on the other hand it can be a real show stopper!
Check out this extensive information @hedda accumulates and that shows all the possible pitfalls zigbee has to offer.
I stick to esphome wifi devices only for now and don’t need to care about anything of that at all. 