Cannot Disable Smart Group Cache

When I set to Smart Group cache timeout to 0, it still appears to take 5 minutes to update. I was able to replicate what I'm seeing on my system on the sandbox Drupal system for 4.4. To replicate the issue:

1. Disable the smart groups cache by going to Administer > Customize Data and Screens > Search Preferences, and setting the Smart Group cache timeout to 0. (according to the help text this should disable the cache)
2. Search for contacts with a new or current membership of a particular type.
3. Create a smart group from that search.
4. If the demo contact isn't in the group, add a membership of that type to the group.

At that point, you would expect that the demo contact would be in the smart group, but they aren't. I discovered this while using the API, but it also happens in the web interface. They will show up in the group in about 5 minutes.

Is there a step I'm missing somewhere? I've tried clearing the caches, but it only works for that instance of the change. If I do it again after clearing, it takes 5 minutes again.