Lack of interest Make xf_user.timezone an enum

[digitalpoint]

Since this column has a specific set of pre-defined values that it can be, it might not be a bad idea to make it an enum column type. It would save about 20 bytes per user record in the database and make searches against the timezone column faster. While not an insane savings, 20 bytes per user adds up when you have a lot of users.

Say for example Facebook migrated to XenForo... with only 1B users (they have more) they would save about 20GB in their database.