Criticism of Webroot is valid, in many tests it scores quite low from what I remember.
Also, the 'lightness' should be portrayed with guarded optimism, Webroot can cause serious issues. One of our MSP competitors recently moved 5,000 systems away from Webroot because of consistent issues, incessant whitelisting requirements and bloaded WRDATA folders consuming SSD drive space. Also, Webroot has been implicated in hiding itself within Explorer.exe to appear lighter than it really is, anyone remember the 10, even 20 times increase in memory usage of explorer.exe when Webroot was used/tested?
HUGE WRData file - Webroot Community
Before you install WebRoot anti-virus
My inlaws were Webroot fans, but I consistently found them infected with PUPS and Harmful Riskware. Each time I opened a ticket with Webroot they wrote them off as 'harmless' files/programs, when it fact I proved they were not harmless. Eventually they ignored my further tickets and some Triple Helix guy said I was too stupid to understand how Webroot worked. He bombarded my email with pie charts, graphs and marketing FUD about this or that super-neurotic-network technologies with fuzzy-AI and Albert Einstein brain encapsulation.
Let's not forget the recent fiasco where Webroot very nearly bricked millions of systems.
AV provider Webroot melts down as update nukes hundreds of legit files
Frankly, I wouldn't trust it. Ever.