Slower DNS responses with big hosts file is something to be expected. The solution is to feed the data to a DNS caching resolver such as unbound or dnsmasq, as

Slower DNS responses with big hosts file is something to be expected. The solution is to feed the data to a DNS caching resolver such as unbound or dnsmasq, as I have explained in reply to UserRights. Answering here also to point out I originally implemented this on a 5y old netbook (Atom CPU, 1GB RAM) because I tend to have a lot of tabs open in firefox, and ABP's memory usage quickly becomes noticeable, and then comes the swapping. Running unbound+nginx scales remarquably well, without hogging too much memory at startup. (Sorry, I don't have access to the netbook right now to report real numbers).