Commands from serial port may be delayed for up to 5 seconds.

[ambrop72]

After turning the fan on from Pronterface by sending M106, it will take up to 5 seconds for the fan to turn on; same goes for turning it off. I haven't tested, but I expect that other commands are effected too.

This bug was introduced by de5dc03 . How about fixing Pronterface instead of adding bugs to Marlin? You have forked Pronterface after all.

[ambrop72]

Fix: https://github.com/ambrop72/Marlin-rrp/commit/7bf4b4e8e687bd8b6615128919ef366f96be7081 . I'm not aware if and how this affects the bug that was being worked around, but I haven't seen any new problems with Pronterface communication.