search for: 11gig

hi, on samba3 a have a directory "foo" with one subfolder "blah". the subfolder contains a huge subtree with lot of files (11gig). if i click on "foo" it takes 10 or more seconds to get the one folder "blah". but if i use the left foldertree of explorer, there are no problems, it's fast. what is the explorer looking for? size calculations? it there a hint or configuration param in the smb.conf to tun...