Of the ones I have around me right now:
- TiBook 1Ghz 1MB L3, 1GB RAM, 4200rpm HDD, OS X 10.4.11 : 59 seconds
- iBook G4 1.33Ghz 14“ 1.25GB RAM, 4200rpm HDD, OS X 10.4.11 : 66 seconds
- iBook G4 1.33Ghz 12“ 1.5GB RAM, SSD, OS X 10.4.11 : 47 seconds
- AlBook G4 1.67Ghz 15“ 1.5GB RAM, SSD, OS X 10.4.11 : 52 seconds
I for one find this quite interesting. The 12" always felt to be the fastest of them, not only regarding boot time. The 14" however is by far the coolest/coldest running of them.
Obviously an SSD makes not that much of a difference in boot times. That leads me to the next question:
Does a 4200rpm HDD use the full bandwith of the P-ATA / EIDE / Ultra-ATA controller / channel?
In my experience the HDDs are able to deliver around 20-30MB/s (40MB/s SSD, as seen in ActivityMonitor) whereas the last EIDE standard Ultra-DMA 6 (Ultra-ATA-133 / ATA-7) was specified (in 2001) for 133MB/s - therefore an SSD should definitely be an improvement.
Alas, Apple was a bit slow in implementing newer EIDE versions :
- 2002 device : Ultra-ATA-66 : 66.66MB/s
- 2004 device : Ultra-ATA-100 : 99.99MB/s
- 2005 device : Ultra-ATA-100 : 99.99MB/s
- 2005 device : Ultra-ATA-100 : 99.99MB/s
--> the controller at least is not at all at it's limits. Who is? The OS? The HDD? CPU?
Maybe Xbench can help (for comparison I chose sequential uncached read 256K blocks):
- 21.26 MB/s
- 24.65 MB/s
- 83.30 MB/s
- 79.18 MB/s
Not bad! An SSD seems to be worth it
after startup. But what happens during startup? Could the CPU be the bottleneck?
Compare the 1Ghz TiBook with the 1.67 AlBook: 59 vs 52, that's too close. Again this proves that neither the controller nor the HDD are the bottleneck. RAM/Memory transfer rate is too similar on all of them. Also keep in mind that the TiBook uses SDRAM where the others use DDR-SDRAM.
Is it the OS? Maybe the OS can't use that much speed as there are too many small files and dependencies... I don't know, but If anyone knows - help me. Please.
Attached are the Xbench results, feel free to include them in your "library"

Attached is also the Xbench of the Mac Mini I use as a daily driver for "comon" tasks (T4F, iTunes, Word, Excel, Entourage, NotationalVelocity + FTP/AFP/PhotoSync/iTunes server) but as I can't really shut it down without loosing too much data (and time) and it is running Leopard I didn't include it above.
A picture of the bottom specifications of the 1.5 Ghz Mini...
(Regarding any technical info: feel free to correct me if I'm wrong)