Do you mean anti-virus software? If so, no need. I don't believe any even exists.
I use the Nook Tablet (similar to the color) and I just make sure to occassionally clear my internet browser cache (cookies, history, downloads, etc). I also will remove apps that slow down my Nook or seem to cause issues.
Just keep things tidy on your Nook Color, but you shouldn't have to worry about using optimization tools to keep it speedy.
Maybe other users may have other suggestions though!
Thanks. Already keep those clear. Guess I am good to go, ummm read.