Disk Hogs in the wild.

I just discovered that Firefox allows web sites to store megbytes of stuff on your hard drive.  This is not those little old cookies, which were in the 100 byte class.  This Cached Web Content is megabytes.  I found I had a whole gigabyte of  "stuff" stored on disk courtesy of Firefox.  You can free up a gigabyte of disk.  From within Firefox click on the nameless button with three horizontal stripes, far right on the task bar.  Click on Options.  Click on Privacy & Security.  Click on Cookies and Site Data.  Click on Clear Data.  Clear the check mark for Cookies and Site Data unless you want to have to log into all your favorite websites (can you find your passwords).  Leave the checkmark in Cached Web Content and click on clear.  It's worth doing this before running anti virus to speed up the scanning.  If anyone knows how to shut down Cached Web Content I would love to hear about it.
   I figured it was time to run antivirus on new desktop, SmallBox by name.  I downloaded the free Malwarebytes V 3.7.1.  The default scan option is quick, a minute or two but doesn't check your disk files.  The  "Custom Scan"  option does do disk files.  That took an hour.  A lotta time spent scanning the gigabyte of Cashed Web Content, courtesy of Firefox. and even more time scanning a gigantic new Windows folder at C:Window\Services\LCU.  The LCU folder is so huge that I googled on the name just to see what it was.  What little info turned up indicates that people know about it.  None of posts explained what it was, and whether I could delete it or not.  It's huge.  Any info would be welcome.
   Malwarebytes tagged a  profile folder to Firefox as malware.  I didn't agree with that call, and told Malwarebytes to leave that file alone.  It did find some seven registry keys and three other files as malware.  I let Malwarebytes quarantine them all.