The big comparo!
Alright, here's my list:
First is the numbers from off to ready-to-use desktop, second is warm reboot to ready-to-use.
B&W G3 w/ G4/500 upgrade, 448 MB RAM: 2:01, 34 (Yes, a warm reboot takes 1/4 the time of a cold start.)
iMac G3 600, 384 MB RAM: 47, 30 (Not nearly as big an improvement here.)
12" PowerBook G4 867 MHz, 640 MB RAM: 72, 72.
eMac 1.25 GHz, 768 MB RAM: 48, 40
And if you want all the gory details, here they are subdivided by 'step'...
1. From power button hit to screen turning on. (Or from screen black to screen on in the case of a reboot.)
2. To when the gray-on-white Apple logo screen adds the 'spinnner'.
3. To the gray-on-white Apple logo screen going away and being replaced with blue.
4. To the 'Mac OS X' box with progress bar.
5. To the login window (as appropriate, only the PowerBook and eMac have multiple users on, I took about 3 seconds clicking and typing in my password on those two, 'x' for the other two computers.)
6. To the wallpaper appearance.
7. To the Menu Bar appearing
8. To the Menu Bar status area filled, desktop icons drawn, ready-to-use.
All times in seconds:
B&W cold boot: 12,46,100,106,x,117,119,121
B&W warm boot: 7,16,25,27,x,29,30,34
iMac cold: 9,14,28,29,x,37,40,47
iMac warm: 4,9,18,19,x,24,26,30
PowerBook cold: 10,16,30,32,35,40,51,72
PowerBook warm: same (really, no improvement at all. In fact, the last step took one second longer, but I'm chalking that up to timing error.)
eMac cold: 14,21,31,33,36,39,41,48
eMac warm: 14,20,28,29,32,35,36,40
Notes: Yes, the PowerBook took significantly longer than the warm boot on the B&W, and either boot on the iMac. It has FileVault on, secure VM on, and has a bunch (6) of programs that start automatically in the background... The B&W and iMac are pretty much stock Tiger. The eMac also has a few (4) programs start automatically. And both the PB and the eMac have Multiple Users, so it takes me a few seconds to click on me and type in my password.
Commentary: So the biggest improvement in percentage is, by far, the B&W. From cold boot to warm boot, it shaves off almost 75% of its time, actually making it the second fastest on a warm boot, where it was by far the slowest on a cold boot. The older Macs also seem to go from off to on faster on warm boot than the newer. (7 and 4 seconds from screen off to screen on on the B&W and iMac compared to 10 and 14 on the PowerBook and eMac.) If you subtract the 'power on test' time (only count from the moment you get the 'spinner' on the Apple logo,) on warm boot, then the B&W is fastest, at 18 seconds; followed by the eMac (20,) iMac (21,) and PowerBook (57.) I imagine that the eMac would be significantly faster if it had Multi-User turned off, and didn't load 4 programs the B&W doesn't.
And I wonder about the PowerBook. Is it the slow hard drive? FileVault? Secure VM? FileVault seems to be a big culprit, as the PB takes 22 seconds from displaying wallpaper to being ready to use, where every other computer takes exactly 4 seconds to do that same step on warm boot.