Opening this issue for general benchmarks / profiling of HEAD - in the hope we can find some of the major bottlenecks before code freeze when it's still possible to get big API changes in.
To get started, I set up a Drupal 6 site, then upgraded it to D7 - with 1,000 nodes.
Front page, 10 nodes, ab -c1 n500
D6: 8.80 #/sec
D7: 7.86 #/sec
D6: 15.54 #/sec
D7: 12.31 #/sec
webgrind screenshots for /node attached.
I'd really like to see some benchmarks on db_insert() / node_save() as well.