After a short while of deleting, adding and updating the registry data, the data becomes fragmented, with data and free space intermingled. This makes registry access slow. Registry First Aid allows you to de-fragment the registry with ease.
The option Compress Registry is available on the home page of Registry First Aid. It starts the registry analyzing to detect which registry files need to be de-fragmented and can be compressed. Finally it shows original registry sizes, size after compression, saved bytes and compression ratio.
You can select registry files you want to de-fragment and click Next. This will require system restart.