Jason Turner discusses in his recent article the size of instantiated template code.
by Jason Turner
From the article:
Back in 2008 I wrote an article on template code bloat. In that article I concluded that the use of templates does not necessarily cause your binary code to bloat and may actually result in smaller code!
However, after spending the last few months optimizing and evaluating ChaiScript I've learned that the misuse of templates, particularly when inheritance is involved, can have a huge impact on code size.