When running the Benchmark Drive feature on an exFAT partition of my main HD it reports random read/write speeds in excess of 900 Mb/s, sometimes exceeding 1Gb/s! As much as I wish this were the real benchmarks, I know that's physically just not possible for an ordinary HD. This isn't only exclusive to my exFAT partition, I also tried the same test on an NTFS partition of similar size and it produced the same results.
I've attached a screenshot of the bug.
Hope that helps!
EDIT: I've added a picture of the bug with an NTFS file system. It happen to be 1Gb/s+ I WISH! Also, exFAT will start to be adopted more and more as files become larger and in general information easily grows out of the GB range. This is because exFAT has improved transfer rates with large file sizes and has a much higher theoretical limit. Don't get me wrong, it's a small difference, but when you're talking about transferring what seems like vast amounts of information now, it will add up and make the difference. That's a few decades off though
OS: Win7 Ult. 64-Bit
D.F: v2.10.424 (64-bit) [latest version as of today, 8/1/2012]