Here are a couple quick tests I ran to show you the difference....
I did these on the laptop I'm using to write this, so the numbers aren't exactly earth-shattering, but the numbers themselves aren't the point; it's the difference between the full-drive and the short-stroked tests that is what is important.
Dell laptop using an Intel C2D 2.66Ghz, 4GB DDR2-800, and the hard drive is a Western Digital Scorpio Blue 320GB WD3200BEVT-75ZCT which runs at 5,400RPM and has a disk cache of I believe 8MB. It is connected via SATA 3Gbps, all drivers up to date on the laptop.FULL DRIVE (ALL 320GB)SHORT-STROKED TO 10% (32GB)
Look at the difference between the two graphs!
For the Full Drive, we get a maximum speed of 64.5MB/sec, with an average speed of 51.4MB/sec, an access time of 17.4ms (avg), and the graph shows the sloped performance curve.
However, when we look at the drive short-stroked to 10% of its capacity, we get a maximum of 67.9MB/sec, with an average of 65.1MB/sec and an access time of only 11.4ms! There is no slope in the performance curve, rather it is effectively a straight line, hovering above the 60MB/sec mark (the sharp drop to 57MB/sec was due to Windows Defender popping up; that is really just a fluke).
Keep in mind: this is a 5400rpm, 2.5" laptop hard drive with a small buffer!
Not to mention, it's pretty well packed with stuff. Here's a shot showing current free space....
So there, as you can see, are the benefits of short-stroking.