I have TAG (techloq) which doesn’t slow down my computer, and is customizable by category.
I think it’s $100 a year.
Another incredible software that I use is Webchaver (Covenant Eyes).
The main idea isn’t blocking websites (though you can also make a whitelist/blacklist, and there is also an option to block adult content, though its very general), rather accountability.
The idea is that no matter how strong a filter is, there are always some ways to get around it (loopholes, Google drive, etc.)
Webchaver puts a system that takes random screenshots of all your activity throughout the day, and emails them to someone you trust. The screenshots are blured so the shomer can’t see sensitive info (emails, accounts, etc.) but gets a general picture of what you’re doing, and can sense if its something inappropriate.
This is very helpful, because even if something is allowed by my filter, I think twice – is this something I want someone to see me doing?
The price and setup is also relatively easy and cheap.