Yes; select all of the records from the tracker table for all of the selected users. Look up the documentation/manual for your DBMS about using JOIN, subqueries, or just using two tables in one query.
That will reduce 451 queries down to one or two.
Although 6-10 minutes is very slow (140,000 records is not large). Do you have any indexes defined (if not, then again consult the documentation for details).
