Note: naming all fields is of course a best practice, but in this post I will discuss only performance benefits, not design or maintenance ones.
The * syntax can be slower for the following reasons:
Not all fields are indexed and the query uses full table scan. Probably not your case: it's hardly possible that all fields you return are indexed with a single index.
Returning trailing fields from a table that contains variable length columns can result in a slight searching overhead: to return 20th field, previous 19 should be examined and offsets calculated.
Just more data need to be returned (passed over the connection).
Since you need almost all fields, the last reason is probably the most important one. Say, the description TEXT field can be only 1 of 50 fields not used on the page, but can occupy 10 times as much space as all other fields together.
In this case it will be of course better to name all fields and omit the long fields you don't need.
