[ic] Very slow [search-region] page

[marco]

An old page with minivend search become very slow. The query is from 
only one mysql table products (159 fields and about 6000 records).

The first result page 1..10 items is quick (3s):
url=cgi-bin/elcat/carr.html?mv_arg=&id=3nqtfXVE&anag=&tecn=&stor=&prez=1&stop=1

All the other subpages 11 .. 20, 21..30 etc etc are very slow (16s) each:
url=cgi-bin/elcat/scan/MM=2a79e8aa45e82fb7361be8a2c995622a:10:19:10.html?mv_more_ip=1&mv_nextpage=carr&mv_arg=&id=3nqtfXVE&field_tf=&field_tf_val=&coord=&reverse=&order_to=&substring=&anag=&tecn=&stor=&prez=1&stop=1

If i put 60 items for page i get "Internal Server Error", the error.log 
of interchange say:elcat - hammered pid 12644 running 300 seconds
and without errors on catalogue error.log

Interchange: 5.6.2
MySql: 5.0.51a
Perl: v5.8.8 built for i486-linux-gnu-thread-multi

Any suggestion ?
Substitution of [search-region] with sql [query] can solve ?

Thanks in advance.

-- 
Marco "Fino alla bara sinpara"
Marco "Up to demise we rise"