dblink slow if select more than 34 fields

Hi.

When using a 'select cursor' with a dblink issued from a Oracle 8.1.6 to a Oracle 7.3.4 database(both AIX/UNIX), I experience extremly slow if the select statement select more than 34 fields; a cursor completes within 2 mins when selected fields not more than 34; if 1 more field is selected, it takes 30 mins to completes.

Any Parameter I could tune ??

Thx.