when I call the page it takes very long because there are filters set by shuttle items and the view of the interactive report is quite large.
So I want the IR-region to be rendered only after pressing a submit button which sets the REQUEST to "APPLY".
This is done by setting the condition of the reports region to "REQUEST = APPLY".
Everything works fine but in the IR-region I've a custom-pagination which calls gReport.navigate.paginate.
And here the REQUEST isn't set to "APPLY" and the page isn't rendered.
I think you can't set own request value, because (it follows from apex_interactive_reports_4_1.js) when IR makes ajax call, it always set the request value by 'APXWGT' for this call, and if you change this call, you IR will not work properly.
About your problem.
Maybe you can make your page less weight. Or divide your page into 2-3 pages?