Performance impact field-order
The order of things in SELECT ... does not matter.

The main performance killers:


Having to fetch from disk.
Fetching more rows than needed.
Fetching more columns than needed.  That is, SELECTing * when you don't need all the columns.
Everything else is relatively insignificant -- expressions, ordering, etc.


In particular...

FROM UserContact u
LEFT JOIN User cu ON cu.ID = u.CreatedByID
LEFT JOIN User uu ON uu.ID = u.UpdatedByID
WHERE u.UserID = ?


Needs these indexes to tackle #2, above (unless they are already the PRIMARY KEYs)

UserContact: INDEX(UserID)
User:  INDEX(ID)


Please provide SHOW CREATE TABLE if you need to discuss further.