I bought this recently for the PSP.
For some reason i remember the loading times being SO much worse on the PSX, but for the PSP it wasn't TOO bad.
I'd say go for it, it is slow, but its not OH MY GAWD WHAT ARE YOU WAITING FOR? CHRISTMAS? Slow.
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NIO BUNNY - http://img.imgcake.com/nio/76ayvpngam.png