CCleaner - drive wiper tool
can be set to wipe an entire drive or just the empty space i.e. where windows thinks there are no files,
can be set for a different number of passes therefore making deletion secure.
will it speed up the drive doing this? unlikely!
the only way to get the drive to work at is fastest speed is to
ensure correct controller is used, in correct mode for IDE drives (DMA rather than PIO), enough free space on drive for caching temp files and defragging the drive to ensure system is'nt searching all over a large drive for parts of files.
If you really want a fast drive then you need a SSD.