simoncastle:
Any how the problem still persists if I set _SS_MAX_RX_BUFF to 63, 127 or anything other than 2^n i still get timing issues.
Im currently using 127 for testing, but will revamp the code to use 16 bit in the end as I may need more than 256.
I agree with the others, that at a high baud rate (when cycles are scarce) doing a lengthy division, twice, isn't going to help.