R: Postgres 9.6.1 big slowdown by upgrading 8.4.22

Hi guys,

really much appreciated your replies.

>> You might want to include the query plans for each server

W e use a function, the explain analyze is quite similar:
POSTGRESQL 8.4.22:

explain analyze select 'record.com' where 'record.com' like '%.%' and function_cloud_view_orari('53', '192.168.10.234', 'record.com') != '' limit 1;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=0.03..0.04 rows=1 width=0) (actual time=1.488..1.488 rows=0 loops=1)
-> Result (cost=0.03..0.04 rows=1 width=0) (actual time=1.485..1.485 rows=0 loops=1)
One-Time Filter: ((function_cloud_view_orari('53'::character varying, '192.168.10.234'::character varying, 'record.com'::character varying))::text <> ''::text)
Total runtime: 1.531 ms

POSTGRES 9.6.1:
explain analyze select 'record.com' where 'record.com' like '%.%' and function_cloud_view_orari('53', '192.168.10.234', 'record.com') != '' limit 1;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=0.03..0.04 rows=1 width=32) (actual time=4.216..4.216 rows=0 loops=1)
-> Result (cost=0.03..0.04 rows=1 width=32) (actual time=4.215..4.215 rows=0 loops=1)
One-Time Filter: ((function_cloud_view_orari('53'::character varying, '192.168.10.234'::character varying, 'record.com'::character varying))::text <> ''::text)
Planning time: 0.046 ms
Execution time: 4.230 ms

There is only one condition that, by deleting, Query in new 9.6.1 Postgresql Server is very fast also on massive benchmark test.
The condition is this:
"exists ( select 1 from gruorari where gruorari.idgrucate=grucategorie.id and ( (('{'||gg_sett||'}')::int[] && array[EXTRACT(DOW FROM NOW())::int])='t' and now()::time between gruorari.dalle::time and gruorari.alle::time) )"

We have a table of "weekly events", as example:
- monday from 12 to 14
- tuesday from 18 to 20
...

What is the best way, on Postgres, to store the information and to INDEX this kind of information?

Thank you, very best regards!
/F