Hello tommybc!
If you're looking on blocking some websites from your children, you can try using the "Parental Controls" of some anti-virus software.
This is good because it doesn't only block the website without using too much resources, it also protects your computer from viruses or malwares.
I personally use Kaspersky Internet Security, and it has a very good built-in parental control option.
You can get Kaspersky Internet Security for as little as $10 on Kijiji or eBay, sometimes even cheaper.
Hope this helps a bit!