Performance of SL and two clients

I recently used the -multiple comand line option for my SL shortcut to run two clients at once. My computer seems to be able to handle two at once except for when the hard disk needs to be cached or written to, as SL does often. My question is this: Does SL use one directory for all caching, or if I place my two copies of SL on two separate hard disks, will each copy use a different HD for caching?

Both hard drives are on different controllers, so they'll have their own separate bandwidth on the motherboard. I'm wondering if using this setup (Say, one on C:\SecondLife and one on D:\Secondlife) will improve HD caching times for running two clients at once or not.

From my personal experience it is less about HD location so much as video memory, RAM, CPU, and bandwidth. Have you tried turning down settings to the minimum and not playing ANY music. I find playing music either by SL interface or using an external program doesn't always agree with dual or even single viewing (winamp got me on this ALOT). I'll admit my results were not fantastic but enough to um...camp for a week straight.

PS I think using two directories does not work. I think then it detects the other "client" and gives you the same error as if you never put the -multiple into the first one.

Even if you did run two instances of SL from two different drives, you'd see little-to-no improvement because all your user information (your SL cache) is stored on your system drive (Usually C:). Plus if you're using so much memory that your operating system needs to page things to hard drive, that's all going to be on your system drive as well.