Grouping large data

I have got 3 huge tables
here is the sample data

table 1
Companyname id year volume_for_jan vol_for_feb.....vol_dec
abc 1 2000 34 333 ......555
2 2000 33 22 666

table 2
Companyname id year volume_for_jan vol_for_feb.....vol_dec
rrr 44 2001 55 66.............888
24 2001 22 35 454

each table has almost 800000 rows

I need to generate a report out of these tables which should be as follows

Company name Id Year Vol_for_jan Vol_for_feb.........
abc 1 2000 34 33
2 2000 33 22
rrr 44 2001 55 66
..................................................

when i try to run the report in business intelligence ,it takes forever to run and doesnt even produce the report at the end...



what shall i do????