Quote from: Colemar on May 16, 2013, 05:34:58 AM
just a guess, but it may be that the 128GB cards are formatted as exFAT, while the <64GB cards are FAT32 and the Canon's firmware is optimized for FAT32..somewhat analogous to the possible 32bit v. 64bit problem with raw2dng.
I already tried that. The card came originally formatted Fat32 and when all my attempts to get faster speed failed, I did a low level reformat to exFAT to see if it faired any better... but there was no significant change in speed (sort of what I expected).