High Receiving Times for HTTP Responses below 500 bytes

[Drit]

While using devtools>Network on Chrome 15 stable on Windows 7 and
Windows XP, I am seeing cases where "receiving" time for an HTTP
response is >100ms but the response is a 302 redirects or small image
(beacons) - with a payload below 500 bytes (header+content).

Capturing the TCP traffic on Wireshark clearly shows the server sent
the entire HTTP response in a single packet, so receiving time should
have been 0. This brings up a few questions:

1. What is defined as "receiving" in chrome devtools? is this the time
from 1st packet to last packet,
2. What factors in the client machine/operating systems impact
"receiving" time, outside of the network/server communication?

A good example is CNN homepage, or any major website that has a lot of
ads and tracking beacons.

In my tests I used a virtual machine for Windows XP, while Windows 7
was on a desktop (quad core, 8gb ram).

thanks

drit