IMHO, the advantages of using a framework far outweigh the disadvantages of any overhead costs that may come with it. Of course there are always exceptions to the rule, these being:
- The project is small enough to not warrant a framework
- The framework itself is horribly designed
But for the majority of cases, you shouldn't worry about it. I've been using Symfony (versions 1.2 & 1.4) on a number of projects, and haven't once thought "this is too resource heavy". I will gladly sacrifice some resources in exchange for all the tools a framework provides that makes my life easier, and the job take less time ;)
