I was always in the mindset that you should always comment your code. It makes it easier to go back in later on and figure out what you’re doing to power the site, easier for someone else to reverse engineer it should something happen to you or the business arrangement, and it allows for freeware code like SWF Object to circulate as comments in the code for those who would look.
Recently, I’ve heard from a few different sources, Lesley, our advisor from More Visibility included, that comments, especially ones with urls, hidden code, or actually any code period is a no no for SEO, and increases load time, and so should be removed.
If the comments are relevant I don’t agree with either of these points as that the potential benefit is not equal to the potential loss, namely ownership and accessibility. I guess my point is, if you had to reduce website load times there are plenty of other ways to do it.