Reg : Table Space on DISC

Dear Gurus

During a table creation we specify the size Category(0-9), in tecchnical settings.

Now my Question is, suppose if i specify size category as say "4" (Data records expected: 16,000 to 66,000) and if I'm storing nearly 500000 records in it, then will a SELECT statement on such a table takes a lot of time to retrieve data form it???

And the thing is.... I'm using nearly 8 tables in a report which consists of huge number of records than specified in the Size category & my report is taking hours to display the o/p,though it is tuned to its best in terms of performance.