Sending code to ESP32 slow using EspruinoTools -- says "Set Slow Write = true"

You'd have to dig around in the code I'm afraid - serial_nodeserial.js for the CLI afaik. Honestly though I have to focus my time on the tools for folks that actually buy Espruino hardware.

From my point of view, I make nothing out of ESP32. Making uploads 50% faster doesn't change anything for me at all - but if 1 in 100 uploads fails with the new code then people come to the forum, email, twitter - and that ends up costing loads of time in support - so this is all super far down my priority list.