1.    21 Aug 2015 #1
    Join Date : Aug 2015
    Posts : 4
    Windows 10 Pro x64 (Insider)

    Windows Defender - Very slow scans

    Upgraded a laptop to windows 10 Home x64 for a family member. It's an older Acer Aspire laptop. We attempted to do a Windows Defender quick-scan to try it out. However, three hours later, it's only ~50% complete. I've never had a fresh install take this long for an AV quick scan.

    My initial thoughts were..
    1) Is the CPU being bogged down? no, only ~80% max during the scan.
    2) Running out of available RAM / swap space? no, only about 60% RAM was being used during the scan

    It's a fairly fresh install (couple weeks old) so I don't think it could be drive fragmentation. However, the computer is kinda old so could it be a failing drive? Am I missing some setting?
      My ComputerSystem Spec
  2.    22 Aug 2015 #2
    Join Date : Jul 2015
    Posts : 899
    Windows 10 Home x64

    That's pretty strange. We all know laptop harddisks are usually slower (5400rpms) but 3 hours is an insane time for a quick scan. Can you check process manager to see if there is anything else running that is slowing things down?
    On my desktop i7 (SATA II hd), Defender takes about 5 minutes for a quick scan.
      My ComputerSystem Spec
  3.    22 Aug 2015 #3
    Join Date : Oct 2014
    In a house with a crazy cat trying to kill me
    Posts : 17,379
    Win 7 32, Win 7 64 Pro, Win 8.1 64 Pro, Win 10 64 Education Edition

    This tool should help you see what is using the most resources.
    Process Explorer shows you information about which handles and DLLs processes have opened or loaded.
    Process Explorer
      My ComputerSystem Spec
  4.    22 Aug 2015 #4
    Join Date : Jul 2015
    Posts : 216
    Windows 10 Pro 64-bit

    Are you leaving Defender open when scanning? I found (a glitch maybe) that leaving it open gives a false timeline. Mine was showing around 50% complete after about 15 minutes, but I closed it, and reopened it, and it was done. I did it again to see, and it seems the display "sticks". The second time I just opened an explorer window, and then click back to Defender, and it was around 90% done in that split second. They were both on quick scans.
      My ComputerSystem Spec


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