CCleaner Professional version (not the free one) offers ‘Real-Time monitoring’ feature, which alerts you when you can save some disk space by cleaning, it has been made available to free users of CCleaner with no control on choosing disk space size for alerting.
Piriform has released CCleaner v4.18 with active system monitoring feature, means, it keeps running in the background without relation to opened CCleaner and prompts you to clean if cleaning saves more than 0.5 GB to you. You can see this feature enabled under newly added ‘Monitoring’ tab in Options (check the screenshot below).
With this feature in place, you can see CCleaner.exe runs on startup and its icon in the system tray on mouse hover shows ‘CCleaner monitoring is active’.
Disabling System Monitoring in CCleaner
Piriform offers the option to disable system Monitoring in CCleaner, you can by
Open CCelaner > Options > uncheck or remove tick mark for ‘Enable system monitoring’.
Disabling the setting hasn’t been honored, you can still see CCleaner icon and its process in Task Manager, seems it’s a bug, hope it will be addressed in upcoming releases.
Currently, the only way you can avoid this monitoring feature in CCleaner is by using portable version, which you can download from Piriform website or consider installing CCleaner v4.17 (FileHippo) on your computer.
Note: After installing CCleaner, when you open it, it shows its name as ‘CCleaner Free’ on top with system specifications.