Maybe connected, maybe not , the new "spot verification service" and the new "online self-healing" model:
Also most probably unconnected, but there are hints that there is something changed at a "lower" level than the filesystem driver (at least when AF disks are involved):
Just for the record, it is not the first time (historically) that for mysterious reasons a filesystem driver (or however *something* influencing data access or transfer speed) is much slower than a previous release, even on a much simpler filesystem such as FAT16 or FAT32:
and however there are so many "queer" behaviours when it comes to "real life" disk speed/access that I guess we could spend an entire lifetime doing tests each one of which will contradict the result of the earlier one.
And this time undoubtedly not connected, but a good example of how sometimes MS changes things (quite relevant) and says nothing about the changes, we have recent evidence that a TexFAT version 2.0 was introduced silently in Windows Phone 7 (or maybe 7.5):