NTFS compression could have been useful if they had used a decent compression algorithm like the famous Oberhumer LZO which decompresses at about 20 MB/s. On a Pentium 133. On a fossilized Athlon from 2005 it does about 200 MB/s. I'll let you check it out on a Core 2. It's faster than a modern harddrive (even when compressing). Compression is decent, too. The other thing is that the cache should cache compressed data which would double the size of your disk cache. But it doesn't.