It looks like MMU2_VERIFY_LOAD_TO_NOZZLE_FEED_RATE can get much higher that the original 20mm/s. 50mm/s is the default now, can be tweaked further.
The Extra Loading Distance is configurable by the user. We need to compensate the hardcoded sequence such that it does not extrude too much or too little. Currently the firmware extrudes too little.