What is the typical speed for those chip with the bootloader ? Maybe it depend what board I select at the IDE level.
Exactly. And if you purse through the various 328p board choices in the board.txt entries you will see that the baud rate used is different for diffent board types. Some of this is legacy values from older boards/bootloaders and of course if the board is using a 8 or 16Mhz clock value.
Now an up side to all this is that any 328p based board or standalone circuit that is running at 16Mhz can have the latest Uno bootloader burned into it and then enjoy the newest fasted upload speed, you will of course then need to select the board type as Uno even if it's an older model arduino board.
That make sense?
Lefty