My Snow Leopard DVD arrived yesterday but I didn't have a chance to install it until this evening.

I actually did an upgrade, upgrading a MacBook Pro from 10.5, and the upgrade itself took about 45 minutes.  One strange thing was during the middle of the upgrade the screen went 90% dim and I could hardly read how much longer it would take.  But alas everything completed without a hitch and the machine rebooted.

Since one of the perks of the new OS is improved performance, I had done a few very unscientific tests on the machine prior to upgrading and then did the same tests post upgrade.  The tests I performed and timed were:

• Boot and login.
• Start NeoOffice.
• Open a simple .ods file from a fully closed NeoOffice.
• Start Safari pointed to the default apple.com page.
• Start Firefox pointed to google.com.
• Open Eclipse.
• Re-open Eclipse from fully closed.
• Transcode a .wmv video to .ogv format.

After these tests I also looked at memory usage to see where things stood.

I did perform the tests on Snow Leopard twice since I was a bit surprised by a few the first time.  Note that in each case the tests were performed in order so everything started from a fresh reboot.

Action	Leopard	Snow Leopard (1)	Snow Leopard (2)
Boot to login screen	40	33	35
Start NeoOffice	23	17	20
Open .ods in NeoOffice	10	12	9
Start Safari (apple.com)	8	5	4
Start Firefox (google.com)	8	8	6
Open Eclipse	17	36	19
Re-open Eclipse	7	7	7
Transcode WMV to OGV (wall clock)	4:52	5:14	4:51
Transcode (user time)	4:48	4:55	4:46
Free (GB)	2.43	2.03	2.14
Wired (MB)	153.5	304.4	162.8
Active (MB)	376.68	524.7	403.3
Inactive (MB)	45.21	157.3	310.7
Used (MB)	575.39	986.4	876.8
VM size (GB)	30.2	104.04	107.73
Page ins (MB)	243.07	916	224.6

• So Snow Leopard boots a little faster, but not dramatically so.  Further, on the first reboot, completing the login took about 5 seconds whereas with Leopard it was just a second or so.  The second test on Snow Leopard was in the 1-2 second range so perhaps it was just something with the very first login.
• It would appear NeoOffice itself starts a bit quicker under Snow Leopard, but opening a spreadsheet is roughly the same.  I'm not sure if anything can really be concluded here.
• Safari certainly starts quicker, I'm not sure if there is a new version that is faster or if they sneakily have it partly loaded/started behind the scenes.  Firefox took basically the same time to start but was perhaps slightly faster under Snow Leopard.
• Oddly, the first time under Snow Leopard, Eclipse took much longer to open than with Leopard.  This was the big reason I did a second test and in that one it was closer to the same time.  I'm not sure if there was something about running Java the first time or what.  In both cases re-opening Eclipse after a full close was the same time.
• Surprisingly the transcoding of the video was slower under Snow Leopard the first time.  The second time it was just about the same.
• The memory management with Snow Leopard seems to be quite a bit different as performing the exact same steps resulted in over 50% memory being used, although in the second test the bulk of this increase was inactive.  But the VM size was over 3 times greater in each case.

As I said at the beginning, not terribly scientific, but at the end of the day it appears the only noticeable improvement is in the Safari initial start time which is less than I had hoped for.  I'll certainly be reading other reviews and looking for other improvements there might be in the coming days.