Webroot isn't the worst going, is really needs to be twinned with anti-exploit protection or a good FW (not the built in one). Not defending because I have this installed, just going from experience having this on my machine.
After 2 days 99MBTried this on my PC and they're right about the lightness, and how the install is around 4MB. Something they don't mention is that anything Webroot is "unsure" about gets put into C:/ProgramData/WRData so it can restore damage done by malware. This isn't a bad thing, but when the option can't be disabled people like me have their 128GB SSD written to constantly and 10+ gigabytes used up. Webroot support say to reinstall and remove the folder, but when you install it again the same thing will happen...