By default, IBM Cognos 8 executes queries in a report sequentially. Depending on the server environment it might be possible to improve report run performance by enabling parallel query execution.
This setting can be adjusted in the advanced server properties for the report service and the batch report service. When concurrent query execution is enabled, the report server determines which queries in the report can be run in parallel.
There are a few parameters that can be adjusted to manage concurrency in Cognos 8:

RSVP.CONCURRENTQUERY.NUMHELPERSPERPROCESS - number of helpers per report service (and batch report service) process. By default the parameter value is 0 (concurrency disabled).

RSVP.CONCURRENTQUERY.MAXNUMHELPERSPERREPORT - maximum number of helpers per report. By default it is set to 1. Has no effect when the above parameter is set to 0.

RSVP.CONCURRENTQUERY.ENABLEDFORINTERACTIVEOUTPUT - enables concurrent query execution when the report service is producing interactive output (disabled by default).