I have a hard drive that I use for storing and working with large tar archives, ranging from less than one MB to hundreds of MB and I have thousands of these archives. It is not convenient to format this drive and start over often, which I do about once every 6 months due to the problem I have. It seems that after a few months of working with these archives, unpacking, making modifications and tarring them back up, the whole system will get very slow, but particularly this drive. Since I cannot find any defrag programs, I'm not really sure what to do other than completely wipe the drive and restore the archives.

Currently, this is an ext4 partition. I do not believe this ever happened with an ext3 partition, but it may have and I've just forgotten. 

Are there any tools I can use to clean up an ext4 partition and recover some speed? Am I missing a defrag tool somewhere?

All my googling is only returning how to recover corrupt partitions and such, but my partitions are not corrupt, that I know of, just slow.

Nathan