I didn’t have the patience to check which version this problem occurred in, but I think it’s a few months old. To reproduce, just disable the Internet connection. Launch CCleaner, go to the “Custom Clean” section then press the [Analyze] button. CCleaner freezes, the OS too, I can no longer access the Start menu in Windows 10 and I have to wait a few minutes for the analysis to start.
I found that CCleaner launches a lot of Internet connections that block the application waiting for information. I consider this problem a bug, the application should be functional immediately, even if there is no Internet connection.
Some parts of CCleaner need internet access to work.
Without it they can not function properly.
If you cut off that access then those parts will still try to access the internet and may take time re-trying when they can’t.
You will also see the same lags (and of loss of functionality of some parts of CCleaner) if you use your Firewalls to block the connections.
You do appear to already know the solution, stop blocking CCleaners internet access so that it can function as it is designed to do.
This problem has appeared recently, as I mentioned in the post, no more that a half of a year. I will downgrade the latest version one by one until I get to the version number where the change occurred. I repeat, I do not always have an Internet connection and waiting a few minutes with the computer locked is not right. There may be people who do not understand what is happening and then they are tempted to press the reset button.
I am using build 6.34 free slim version.
I installed this without an internet connection and I run it every time as custom clean without an internet connection.
I have no locked process when doing so (eg I can open Windows Task Manager while doing a clean)
I have ccleaner scheduled tasks for updater and crash reporter deleted in Windows Task Scheduler