Why do you no longer support Windows XP or Vista?

Why we've stopped supporting XP and Vista:

XP and Vista users now make up a tiny and diminishing fraction of our user base. As such, we have decided to focus our efforts on making CCleaner the best it can be for the overwhelming majority.

What this means if you use CCleaner for Windows: 

If you are using XP or Vista, v5.64 is the last version of CCleaner you can use. If you try to update to a newer version of CCleaner, you will not be able to. However, v5.64 will receive any critical security updates.

What this means for the future of CCleaner:

No longer supporting XP or Vista on newer versions of CCleaner allows us to move to new technologies that deliver a better experience to millions of users.