Eugene's observations

A steady trickle of jobs continue to come my way after the owner has tried to resolve their issue or improve performance by running a registry cleaner.

At best, registry scanners can highlight something for further investigation by a skilled specialist technician (more skilled than the author of this note). At worst, and not uncommonly, they can trash your system to such an extent that reformatting the hard disk drive and reinstalling Windows are your only sensible course.

To work as often claimed, these tools would have to have intimate knowledge of every version of every program installed, and their interactions. They typically work by removing orphaned links and obsolete pointers to save space, but for what ?

In a worst case scenario a Windows registry may be so fragmented and large that several I/O operations are required to load it at start time. Even if 10 such operations were required, the time to do so would be sub-second.

The aim of many such programs seems to me to be to scare unwitting folks into paying for something that they don't need or accept unwanted advertising. A far better investment would be to have a PC professionally serviced as that would include performance enhancements and some problem resolution.