I didn't realize that Mozilla made their Firefox field performance stats public. Lots of awesome RUM data at http://telemetry.mozilla.org/
Here are some of my favorites for using as a baseline for your own RUM metrics (setting goals, etc). Make sure to change the preferences to show evolution over calendar dates and un-select any percentile that has a huge spike to make the graphs cleaner:
Page Load Time: http://telemetry.mozilla.org/#release/26/FX_PAGE_LOAD_MS
Median is 1.3 seconds and the 95th percentile is 10 seconds (actually a lot better than I expected)
DNS Lookup Time: http://telemetry.mozilla.org/#release/26/DNS_LOOKUP_TIME
Median is 45ms but the 95th percentile is 660ms - that's scary-long.
The RTT measured from the SPDY layer (couldn't find the TCP equivalent but it may be in there): http://telemetry.mozilla.org/#release/26/SPDY_SETTINGS_RTT
104ms median and 473ms 95th percentile. Could be lower than the DNS numbers since SPDY is dominated by large sites right now (Google, Facebook, Twitter).+Patrick McManus
Do you know if the TCP socket connect time is in there anywhere? That is usually a great proxy for the RTT.