Early 2008, 4,1
Early 2008 Penryn: 6GB RAM, 2.4 Ghz Intel Core 2 Duo, 1TB HDD.
Mavericks after a week is running incredibly smooth, best ever in fact.
Scrolling up and down in the browser it just "coasts" and it feels like a "new computer."
Someone very talented has redone the memory usage and the interface with the HDD is well integrated. I'm seeing about a GB virtual memory used in the HDD but everything is running smoother and cooler.
My regular usage would see some fan activity engaged and temps would be in the mid 60s and 70s or higher centigrade with my typical use (lots of tabs open in Safari and/or Chrome).
With about 10 tabs and some other apps open, temps are in the low 50s!
That's some really impressive work behind the scenes in the OS.
The laptop which typically couldn't be used as a laptop without some filler due to heat can now be used comfortably on your lap.
I'm extremely impressed with Mavericks.

Hat tip: programmers on the Mavericks team.
