Why is File Upload slow in IE when SSL being used?

Question

Boy do I have a strange bug. I have a website that needs to upload large files. We are using the standard ASPx FileUpload control. We have modified the web.config to allow really large files.

I am doing all these tests in FireFox, IE6, and IE7. For my test I am using a few 20 MB files (AVI, PDF, Excel). The file type does not affect the results. I can upload these files just fine in all browsers with about the same results. Each file takes between 30 and 40 seconds. If I turn on SSL on my website, the code still works, but the upload in IE takes 5 to 10 times as long. Everything works, it is just way slower. I used file monitor, and it looks like IE is reading the file 3 times. FireFox reads it only one time. I also have noticed this slowness in IE occurs on PCs with Office 2003 or 2007 installed.

How often does IE wants to renegotiate the SSL keys? Can I change this? Why would FireFox be so fast? Most of my users have IE, so this is a real pain.

Any ideas?

Thanks.

Answer 1

The first thing I would do is fire up fiddler and observe the converstations between the server and the browsers to see if there is any difference in behaviour.

Caveat: Fiddler can actually actually change the way SSL works so it may not be fully trustworthy guide but it might give you clues as to where to look.