smarq8:
Also I want to know is it possible to increase speed yet more?
Yes. I know there is a board definition in the Mighty 1284P hardware package that runs the bootloader at 1 Mbps and I never heard reports of people having problems with it. The easiest way to play with higher bootloader speeds is to install MiniCore:
It comes with bootloaders compiled for a variety of speeds up to 1 Mbps. It uses 115200 as default so you do need to edit boards.txt and change 328.menu.clock.16MHz_external.upload.speed= to your desired speed, then it automatically updates the bootloader file name from that property. The available speeds are:
- 9600
- 19200
- 38400
- 57600
- 115200
- 250000
- 500000
- 1000000
You need to restart the Arduino IDE before changes you make to boards.txt take effect.
If you want a different baud rate then you will need to compile the bootloader from source, which is not so difficult.