Today I had to upload a big file (over 15 MB) and I had some problems with uploading. I tried different applications. Accidentally, I had Windows Task Manager opened while uploading and noticed interesting patterns.
This is how downloading file with Internet Explorer looks like.
Upload to ASP.NET page with with Internet Explorer.
Upload to SharePoint page with with Internet Explorer.
Upload to ASP.NET page with with Firefox.
Sending e-mail with Outlook Express.
Uploading file with FileZilla.