I'm currently using a blacklist off https://github.com/StevenBlack/hosts, which has 50,000+ domains. However, I'm finding that my DNS Client CPU usage is abnormally high.

Does a large hosts file cause high CPU usage?

If so, apart from browser plugins, what are some alternatives to using a hosts file to blacklist certain domains across the whole system?

Edit: Windows 10

  • Is this windows or linux? Linux has ipset inconjection with iptables. My list is 600,000+ long and growing.
    – cybernard
    Apr 29, 2018 at 5:44
  • 2
    remove the large hosts file and see if works normally again.
    – Keltari
    Apr 29, 2018 at 5:46
  • @Keltari Yes CPU usage goes down when removed. Apr 29, 2018 at 6:48

2 Answers 2


This issue can be successfully resolved via regedit by removing 'DNSCache' entry from NetworkService REG_MULTI_SZ at:

  1. HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Svchost

  2. HKLM\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Svchost

Prior to this I had to wait ~10 minutes for SVCHOST DNS Client to complete its process when using Steven Black's hosts file. After making this change, I no longer have to wait. Enjoy....


disable (stop) DNS client, you do not need it in Windows

you may have also high CPU with large hosts with disabled DNS service, caused by explorer.exe (probable related to some antivirus)

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