I found a very good post which demonstrate how to integrate dompdf in CodeIgniter.
CodeIgniter Wiki – PDF generation using dompdf
For some unknown reasons, i found that the the pdf_create() function will get stuck when i try to create a pdf file and this results in timeout error. I located the problem which is caused by $dompdf->render(). After searching for a while. i finally found the failure reason @ Google Groups dompdf – Max execution time error.
The timeout problem occurs when your pdf template view file has a nested table! The problem is resolved after i removed the nested table.