how to improve performance

[riskassure]

Hello, I developed a report using Report Studio in Cognos 8.4. Basically, I have one massive master query that generates all the data I need for the report. There are about 30 or so pages, and each page contains about one or two tables or charts based on this master query (enclosed is a screenshot of part of query explorer). When I want to just view the data, I run the View Tabular Data, and the resulting table usually returns after a few minutes (no more than 5 minutes). However, when I run the report in PDF, sometimes it could take over an hour to run. I am under the impression that when the report is run, Cognos first runs the master query, saves the result locally or somewhere, then use the results to produce tables and charts on each of the pages. Perhaps that's not the case? Maybe Cognos re-runs the master query each time whenever a table or a chart calls for it?? Does anyone know why it's taking a long time to run? Any idea on how to improve report running performance?

Thanks in advance!

~~CW~~