Report Engine is very slow

Hi,

We are using Birt Report Engine in our Java application to print reports to pdf.
But Task.run is very slow. it takes 30 seconds to build a report of 3 pages for the first time.for the second time it takes only 2 sec to generate the report.

Is there any way to minimise the report generation time when we print it for the first time?

Please let me know if there is any way to optimise the report engine.

I have attached birt engine.

We have used scripted data source and BIRT Designer Version 3.7.2.v20120213.