How to join tables on regex — performance test

gistfile1.sql

                                                                                QUERY PLAN                                                                    
--------------------------------------------------------------------------------------------------------------------------------------------------------------
 Nested Loop  (cost=0.00..6275.34 rows=882 width=163) (actual time=0.448..1058.363 rows=75615 loops=1)
   Join Filter: (((msg.src_addr)::text ~~ (('380'::text || (mnc.code)::text) || '%'::text)) OR ((msg.dst_addr)::text ~~ (('380'::text || (mnc.code)::text) || 
   ->  Seq Scan on sms_mobilenetworkcode mnc  (cost=0.00..1.18 rows=1 width=7) (actual time=0.014..0.042 rows=12 loops=1)
         Filter: (length((code)::text) = 2)
   ->  Seq Scan on messages msg  (cost=0.00..4064.76 rows=88376 width=159) (actual time=0.005..16.282 rows=88382 loops=12)
 Total runtime: 1064.521 ms
(6 rows)

Time: 1069.885 ms
                                                        QUERY PLAN                                                         
---------------------------------------------------------------------------------------------------------------------------
 Nested Loop  (cost=0.00..5833.46 rows=442 width=163) (actual time=1.122..3319.321 rows=75615 loops=1)
   Join Filter: ((((msg.src_addr)::text || '+'::text) || (msg.dst_addr)::text) ~ ('380'::text || (mnc.code)::text))
   ->  Seq Scan on sms_mobilenetworkcode mnc  (cost=0.00..1.18 rows=1 width=7) (actual time=0.013..0.048 rows=12 loops=1)
         Filter: (length((code)::text) = 2)
   ->  Seq Scan on messages msg  (cost=0.00..4064.76 rows=88376 width=159) (actual time=0.006..18.095 rows=88382 loops=12)
 Total runtime: 3325.756 ms
(6 rows)

Time: 3336.726 ms
                                                           QUERY PLAN                                                            
---------------------------------------------------------------------------------------------------------------------------------
 Nested Loop  (cost=1.13..237378.53 rows=530256 width=163) (actual time=0.222..12925.048 rows=75615 loops=1)
   Join Filter: (SubPlan 1)
   ->  Seq Scan on messages msg  (cost=0.00..4064.76 rows=88376 width=159) (actual time=0.007..29.841 rows=88382 loops=1)
   ->  Materialize  (cost=1.13..1.25 rows=12 width=7) (actual time=0.000..0.002 rows=12 loops=88382)
         ->  Seq Scan on sms_mobilenetworkcode mnc  (cost=0.00..1.12 rows=12 width=7) (actual time=0.002..0.004 rows=12 loops=1)
   SubPlan 1
     ->  Function Scan on regexp_matches x  (cost=0.00..0.20 rows=1 width=0) (actual time=0.011..0.011 rows=0 loops=1060584)
           Filter: (y[1] = ($0)::text)
 Total runtime: 12938.736 ms
(9 rows)

Time: 12958.897 ms