Having nothing better to do and being a new mac user, I thought I would test how Safari and Firefox compared speed wise. Test was done at
http://www.dslreports.com
Results (test run within 15 seconds of each other) for one run only were 2438/433 for Safari and 2541/433 for Firefox. This of course proves nothing. Multiple test would be required at different times and on different days. Result will vary depending on the number of hops, so test a server closest to your connection and at the one most distant. The throughput noted above was via a server only 9 miles a way in LA. Connections to the east coast will give quite different results.
Draw your own conclusions as to which, if either, is consistently faster.
Use any browser(s) you wish for comparisons.
At http://www.dslreports.com/faq/7136 you can get info on how to tweak your browser for the best performance.
Among other things, the test will report your performance compared to others using your IP.

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