Recently I have noticed that CCleaner takes too long to Launch the " General Users Interface " even though it starts and runs on Windows 10 startup fine .
So I searched the File Location and found a Folder called " BackupStorage " ( Program Files\CCleaner\Data\BackupStorage )
This folder holds Compressed data like Realtek Audio or NVIDIA Drivers .
I had 3 old compressed version of NVIDIA Drivers . Around 1gb
I removed them .
Now CCleaners GUI pops up right away .
Hope this helps CCleaner Team to make an Update to fix this bug .