The professors statement was a sweeping generalization. Sweeping generalizations are rarely true in all cases. You should always think about your resources.

A good thing about languages/systems that garbage collect memory is that you don't have to worry about deallocating memory when you're done with it. This is great because you most likely avoid dreaded memory leaks that can be difficult to find. This is especially beneficial when the developer does not have much experience managing memory.

On systems that don't garbage collect memory you have to be smart and do it yourself. When you have to manage all of your memory you probably have more control over what, when and how much you use. Many of these languages can be faster if the developer knows what (s)he is doing.

In short you want your application to run quickly and efficiently and not be a resource whore.

VB is great for what VB does, C/C++ is great for what it does, DBMS are great for what they do. And since I'm posing on perlmonks I better say Perl is great for what it does! You just need to choose the right tool for the job. I wouldn't use VB to write a device driver. Personally, I'd use Visual C++ to do it on Windows. Don't use a screwdriver when you need a hammer and vice versa.