Francois: TOAO's application was Photoshop CS6, for which he expected running under Mountain Lion would be slower than under Snow Leopard. If our application is FCP7, then it behooves us to run some speed tests in FCP7.
I just now tried exporting a sequence of tiffs from a 5000 frame clip in FCP7. For compressed tiffs it took 5.4% longer under OSX 10.8.3 than under OSX 10.6.8. For uncompressed tiffs it took 9.5% longer under OSX 10.8.3 than under OSX 10.6.8. Whether this is consistent with TOAO's web transfer thesis I know not.
My OSX 10.6.8 and OSX 10.8.3 were fresh OSX installs, with the same FCP7 added to each.
An operating system is general; it must run all programs and perform all services for all users. Mac's user base being what it is, what do you expect?
Dennis Couzin
Berlin, Germany
P.S. Another test: FCP7 rendering of Broadcast Safe Filter took 9.3% longer under OSX 10.8.3 than under OSX 10.6.8.
P.P.S. Another test: FCP7 SmoothCam Analysis took 1.1% longer under OSX 10.6.8 than under OSX 10.8.3, a bit of a counterexample.