You are probably timing out because the rendering engine is not designed to build that many pages.

I have to agree with Lowell, this needs to be broken down into several reports. If you can cram 100 rows onto a page, the report will have 6000 pages, more likely 50 rows per page and 12000 pages. There is no human that is going to look at a report like that.....ever. At best they will scan for certain details. It will be better to simply give them what they really need.