wheel - 3:57 pm on Mar 14, 2011 (gmt 0)

Turn gzipping on at the host level and forget about it. Gzipping isn't perfect in 100% of cases, but it's almost perfect in 99% of cases just by having it turned on.

You're more likely wasting time figuring out idiosyncracies of the measuring tool. And that's going to be futile - and pointless even if you do.