Thanks to members who have participated in this thread.
I think CCleaner is very good as a small file to quickly clean up every day or two. However, if you have an old computer may which have slowed for a variety of reasons, perhaps a few mal files or redundant software has accumulated. In that case a thorough clean up could be beneficial.
Members recommended a program called Iobit Advanced Care System or Glary Utilities. It offers a range of checks and applications . I've taken the advice, ran it through two 5 y.o computers and 4 y.o. lap top.
Lap Top. Spyware: 29 problems, Registry fix: 516 prob, Privacy : 69 prob, Junk Files: 152 MB. System Optimization: 81 prob, Security: 6,350 prob.
Computer A. Spyware: 1 prob, Registry fix: 139 prob, Privacy : 5 prob, Junk Files : 35 MB. System Optimization : 80 prob, Security: 3,950 prob.
Computer B. Spyware: 0 prob, Registry Fix: 97, Privacy: 6 prob, Junk Files: 455KB, System Optimization: 30 prob, Security : 951 prob.
Program has many other ie defrag, updates etc. It initiates a return point if things go wrong.
A few old problems remain but so far, I haven't found any necessary files were removed. All computers appear to be running marginally faster with a little extra memory added.
Thanks to members help and suggest this free program has more positives than negatives. Especially for the less technically savvy such as myself.