5400 RPM, basically the worst speed.
Server's emulator has nothing to do with it. You must make several tests on a server that exceeds population over 600, especially sieges. I'm playing Lineage II without a freaking problem, but when it's about sieges and there are more than 200 in my range, my HDD is crying.
Some of you didn't notice that, but Phobiaa has a good point of view, it's freaking old and not very well designed when it comes to these issues. You'll never play it perfectly with their recommended system requirements.
I've made some tests on Interlude, I've increased client's cache and a few more edits on nwindow.dll, and you can see the improvements; the client is loaded 2x faster, the way it's running, teleporting faster and less lag in pvp.