Comment 9 for bug 203217

Your chmod workaround has simply disabled NIS and automounting, removing all network user and filesystem access from your system. That will certainly solve the problem, but for most people who have this problem, that's throwing out the baby with the bath-water. There are also more standard ways to turn off services.

After having lived with this for a while, I think the core problem is not the user list itself, but the fact that the user-switcher wants to look at everyone's home directory. If there are 10,000 users (not as uncommon as you'd think), this means 10,000 network directory lookups (possibly more if it's looking at subdirs as well, I'm not 100% certain what it's fetching other than a potential icon to use for the login session). I discovered this when I went to my automounted /home directory and found all of the users pre-mounted, which should only happen if I'm actually reading their directories.

Perhaps the right thing to do here is to simply add in some delays. It doesn't have to search all of the user homedirs at once, does it? Would pausing for 500ms between lookups hurt anything? What's more, is it even useful to be looking up fast-user-switch info when there are thousands of users?