> I was under the impression that Rob van der Heij (I think) > had in fact measured DCSS to be slightly faster.
I'd also observe that DCSS swapping may avoid a SIE drop, but as others have mentioned, if you're worrying about that size of overhead, you're already so far up the creek that it's probably not going to matter. DCSS swapping is also much more difficult to configure and manage than VDISK, so it comes down to whether your time is more expensive than some loss of efficiency.
