I agree with Glen. My concern regarding DRM doesn't have anything to do with computer performance, it's mostly about concern over the future if I decide to replay a game.
One major gripe I have with a game that I have with DRM (Batman: Arkham City, specifically) is that it has a limited number of installs that come with the game (it came with my graphics card, so I'm not too upset over it, but I never would have purchased the game myself). I only discovered this after installation, so now I feel obligated to keep it on my hard drive for as long as I can, since I have a habit of replaying/re-experiencing games I enjoy.
I know it's been mentioned that Cognition only has a key activation, with a possibility of offline override, but in the event I lose track of Phoenix Online or am unable to contact them for some reason if/when activation servers are gone, Cognition will either become a hard drive burden for the remainder of the life of my HD or I'll just be unable to re-experience the game, period.
I definitely understand the desire to protect your work from lost sales, so thanks for being willing to discuss this topic.
(Reading back on my response, Glen phrases his post more clearly than I did.)