NTFS compression might cause performance degradation because a compressed NTFS file is decompressed, copied, and then recompressed as a new file, even when copied inside the same computer. Similarly, on network transfers, the file is decompressed, which affects bandwidth as well as speed.
The current implementation of NTFS compression runs more efficiently on Windows 2000 Professional than on Windows 2000 Server. Compression on a computer running Windows 2000 Professional does not seem to produce a substantial performance degradation. Heavily loaded servers with considerable write traffic are poor candidates for data compression, while read-only, read-mostly servers, or lightly loaded servers might not see significant performance degradation.
The two ways to measure the performance of NTFS data compression are size and speed. You can tell how well compression works by comparing the uncompressed and compressed file and folder sizes. For more information about using the DirUse program to see the compressed size of folders see "File System Tools" later in this chapter.