At this point if you're using Windows 10, Windows Defender is probably your best bet. It is dramatically improved over previous generations and tends to use fewer system resources when compared to other programs. If you're truly having problems because of visiting bad websites, there are various DNS filtering tools you can use to keep yourself safer. You can use a guest account on your computer that prevents new programs from installing without administrative privileges. Finally, you can virtualize any Linux operating system (VirtualBox, VMware) and surf the internet there.