Why is the hard drive so slow?

[Foxglove9]

I've been reading up a bit about hard drive speeds and brands. So I decided to run xbench and measure the resultsd of my 3 hard drives. What I can't figure out is why my macbook drive is that much slower. I know it's 5400 RPM but I didn't think it would be almost half as slow?

Powermac G5 1.8 ghz (single core) w/ 2.5 gb ram
Internal SATA - Maxtor 7200rpm 200gb (158 free) = scored 93.33
Internal SATA (2nd) - OEM 7200rpm 80gb (48 free) = scored 51.81

Macbook C2D 2.18 ghz w/ 2 gb ram
Internal SATA - Fujitsu 5400rpm 120gb (80 free) = scored 36.26

 

[mkrishnan]

It seems pretty typical... most of the results posted on the xbench site peg it at around 40. As I understand it, beyond the 5400/7200 issue, 2.5" drives are intrinsically also slower because the circumference is typically less (because the disk has a smaller radius). So if you think about it, on a typical track of a 7200 RPM 3.5" drive, the path length is longer per revolution than on a 2.5" drive of the same rotational speed. So the 3.5" drive reads more on each of those 7200 rotations.