NT4 fast and Win2K/XP slow for browsing

Ok we have a directory that contains log files and it has over 9,000 log files in it. If I map a drive and open it up on NT4 it takes only about 5 seconds to display the entire directory but if I use either Win2K or XP Client to do the same then takes forever. Whats the difference? Does Win2K and XP verify security/permissions on every file and NT does not or what? How can I speed up the Win2K/XP systems to browse this as fast as NT4?

Thanks in advance for any help you can provide