There is not only a difference with real and virtual folders.
A lot of macros doesn't matter if they need not to be invoked repeatadly. But you will notice if you have huge macros in the files dependent section!
What especially increases memory usage (and cpu power) are the use of ?recursive and search. Also the construction of single pages with large filelists, especially if they contain images and thumbnails eat up a lot of memory.
With normal use and pages with not to much content, memory usage in my case is between 5 and 15 Mbytes, but creating huge lists with recursive it can go to 50...100 Mbytes!
What might be a bug, is if hfs uses a lot of memory to build a page, it doesn't release the memory which is not more used. So, after a recursive search, hfs still retains for example 40 Mbytes, even if all clients are disconected!
So i think if you have some users are requesting a recursive listing or search, your some hundred Mbytes uses by hfs is completly normal.