Launch Windows, open a folder or file, install, remove or run a program – just about everything you do on a PC results in Windows writing to the Registry. And over time that means the Registry files will grow, as they contain more and more “slack space”, gaps where old entries used to be.

This isn’t particularly harmful, but it does waste a little memory and hard drive space. And so you might like to try Tweaking.com’s Registry Compressor, a small and simple tool which can defragment your Registry, removing this slack space (nothing else – this isn’t a Registry cleaner) and cutting the files down to size.

The defragmentation process isn’t particularly difficult or dangerous, but plainly if there is a problem, and the Registry is corrupted, then it could trash your PC. And so we’d recommend caution. Only run Registry Compressor on a system which has been fully backed up. And close down all running programs before you launch it, too (you’ll want to minimise Registry activity while the program runs).

How fragmented is your Registry? Find out with a click

With that done, fire up Registry Compressor, click Analyze, and after a few seconds it’ll present some figures on how bloated your Registry files might be. This can deliver some apparently dramatic results, with for instance some of the smaller files on our test PC being anything up to 9 times larger than necessary. Overall, though, fragmentation wasn’t a major problem: the total size of our Registry was currently 172MB, and Registry Compressor claimed it could reduce this to 168.99MB, a 1.75% saving.

Still, if your system shows a larger figure – or you’re just thinking that “every little helps” – then all you have to do is click “Compress”. After a second or two (it’s very quick) the program will tell you it’s done, and recommend you reboot. And as we’re not quite sure how this defragmentation will affect processes which are currently accessing the Registry, it’s probably a good idea to do this right away.

Once our system had restarted, we ran Registry Compressor again, just to see what its analysis revealed now. And sure enough, it seemed to have worked, as our fragmentation had dropped to 0.1MB, or about 0.06%.

Is this worth the effort? We saw no obvious performance improvement, but perhaps that’s because our test system wasn’t too badly fragmented in the first place.

If you’d like to try Registry Compressor on your own system, though, it’s very quick and easy (a 335KB download, no installation required, no adware), and simply seeing a report on the degree of Registry fragmentation could be interesting. Just be sure you use it with care; backup your system and close programs beforehand, and reboot your system immediately afterwards.