Function execute slow down in 9.2 - Mailing list pgsql-performance

Hi!
I can't explain why function is slow down on same data.
Postgresql.conf the same, hardware is more powerful.
Diffrents is postgresql version

Here it;s my tests

Server 1 PSQL 9.1

FIRST RUN
EXPLAIN (ANALYZE, BUFFERS)  SELECT webclient.prc_ti_cache_alloc_dbl_update(
     21325134
);

'Result  (cost=0.00..0.26 rows=1 width=0) (actual
time=1399.586..1399.587 rows=1 loops=1)'
'  Buffers: shared hit=40343 read=621'
'Total runtime: 1399.613 ms'

SECOND RUN
'Result  (cost=0.00..0.26 rows=1 width=0) (actual time=42.540..42.541
rows=1 loops=1)'
'  Buffers: shared hit=37069'
'Total runtime: 42.558 ms'

THIRD RUN
'Result  (cost=0.00..0.26 rows=1 width=0) (actual time=198.893..198.894
rows=1 loops=1)'
'  Buffers: shared hit=37069'
'Total runtime: 198.908 ms'


Server 2 PSQL 9.2

FIRST RUN
EXPLAIN (ANALYZE, BUFFERS)  SELECT webclient.prc_ti_cache_alloc_dbl_update(
     21325134
);

'Result  (cost=0.00..0.26 rows=1 width=0) (actual
time=1328.103..1328.104 rows=1 loops=1)'
'  Buffers: shared hit=43081 read=233 written=36'
'Total runtime: 1328.129 ms'

SECOND RUN
'Result  (cost=0.00..0.26 rows=1 width=0) (actual
time=1699.711..1699.712 rows=1 loops=1)'
'  Buffers: shared hit=42919'
'Total runtime: 1699.737 ms'

THIRD RUN
'Result  (cost=0.00..0.26 rows=1 width=0) (actual
time=1907.947..1907.948 rows=1 loops=1)'
'  Buffers: shared hit=42869'
'Total runtime: 1907.965 ms'