PostgreSQL UUID type performance

We had a table with about 30k rows that (for a specific unrelated architectural reason) had UUIDs stored in a text field and indexed. I noticed that the query perf was slower than I'd have expected. I created a new UUID column, copied in the text uuid primary key and compared below. 2.652ms vs 0.029ms. Quite a difference!

 -- With text index
    QUERY PLAN
    Index Scan using tmptable_pkey on tmptable (cost=0.41..1024.34 rows=1 width=1797) (actual time=0.183..2.632 rows=1 loops=1)
      Index Cond: (primarykey = '755ad490-9a34-4c9f-8027-45fa37632b04'::text)
    Planning time: 0.121 ms
    Execution time: 2.652 ms

    -- With a uuid index 
    QUERY PLAN
    Index Scan using idx_tmptable on tmptable (cost=0.29..2.51 rows=1 width=1797) (actual time=0.012..0.013 rows=1 loops=1)
      Index Cond: (uuidkey = '755ad490-9a34-4c9f-8027-45fa37632b04'::uuid)
    Planning time: 0.109 ms
    Execution time: 0.029 ms

A UUID is a 16 bytes value. The same as text is a 32 bytes value. The storage sizes are:

select
    pg_column_size('a0eebc999c0b4ef8bb6d6bb9bd380a11'::text) as text_size,
    pg_column_size('a0eebc999c0b4ef8bb6d6bb9bd380a11'::uuid) as uuid_size;
 text_size | uuid_size 
-----------+-----------
        36 |        16

Smaller tables lead to faster operations.