memory management

All,

I've written some functions that use a list and a 
list of sub-lists and I'm running into memory problems,
even after changing memory.limit.   Does it make 
any difference to the handling of memory if I use 
simple vectors and matrices instead of the list and
list of sub-lists?  I suspect no, but just want to 
check.

thanks!
Dave

ps - please reply to afshar at miami.edu