Hi Jann, welcome and thanks for your work on analyzing and improving the apt performance! [..] > +/* for Hex2Num */ > +static unsigned char hexdigits[256] = > + {99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99, [..] > + if (digit1 == 99 || digit2 == 99) Tiny nitpick, I would love to see something symbolic (a define or const) here instead of "99". Like "ERR" or "INV" (invalid) or NaH (Not-A-Hex) or something. Cheers, Michael