Fix lag when changing menus

[Insprill]

When switching the mod you're currently looking at, there's a period of a few seconds where the whole application freezes. This isn't caused by the application re-scanning the file system for mod info, as the update functions aren't called and the data remains out-of-date if changes are made. The duration of the freeze appears to scale with the number of list items preset, so that's probably a good starting point.

[Insprill]

Possibly related: linebender/druid#2281