PDF creation using iTextsharp taking too much of time

问题

Iam using ASP.Net along with iTextsharp to generate PDF files. Data is returned from SQL Server in to ASP.Net in the form of a DataTable. For example if my datatable contains 1000 records with varying company id and branch id, my requirement is to write PDFs grouped by companyid and branch id.

CompanyID     Code    Name   BranchId   Amount
1             XXXX    xxx      10        XXXX
1             XXXX    xxx      20        XXXX
5             XXXX    xxx      20        XXXX
1             XXXX    xxx      10        XXXX
1             XXXX    xxx      10        XXXX
2             XXXX    xxx      30        XXXX
5             XXXX    xxx      30        XXXX
3             XXXX    xxx      20        XXXX
1             XXXX    xxx      50        XXXX
4             XXXX    xxx      20        XXXX
6             XXXX    xxx      20        XXXX
4             XXXX    xxx      10        XXXX

My main problem is that its taking too much time to generate PDFs. My logic is simple:

foreach companyId in distinct Companylist
    foreach branchid in companyId
      Populate data based on a HTML template
      Write the HTML output to PDF using iTextsharp
    loop
loop

Is there any better approach? For 200 records, it took 30minutes to generate the PDFs. How do I minimize the time. Please help.

来源：https://stackoverflow.com/questions/38739843/pdf-creation-using-itextsharp-taking-too-much-of-time