It should be faster.. as latency is lower.
I can feel the difference in performance between a 5400 and 7200 drive on a PC that's doing intensive HDD reads.
I suggest that you consider these cons of buying a 7200 drive instead of a 5400 for your PS2:
-People recommend 5400 RPM drives because they don't heat up as much (May not be true anymore due to improvements in technology).
-People have already hacked HDL to have slower read speeds, because HDL with 5400 RPM disks area already too fast for some games(And require slower read speeds that are much closer to the DVD drive's speed).
Should be faster than a 5400, but may not be noticeable (Depending on the game).
The original PS2 hard drive speed was 5400 so how much faster are load times with a 7200?? I want load times to be at least the same as it is from dvd/cd or faster. Not slower.
The Network Adaptor + 5400RPM disk is already much faster (Sometimes even too fast) than the DVD drive's read speed, so you're wrong here.
In case you don't see my point:
HDD's transfer rate(maximum): 66MB/s (If it's operating in ATA-66, otherwise it's 100MB/s in ATA-100)
DVD drive's transfer rate(maximum): ~5.4MB/s
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