I found the .NET setting that controls the size of the AVFP upload in .NET. In the AVFP upload tests that I've run from ASP.NET,
the speed seems to be smoking. These are uploads under 4MB which is the default limit. To allow it to upload larger files,
here's what needs to be done:

While uploading a file to the web server, we have a limit of 4MB by default.
We can either decrease or increase this value. The value is set in the key,
maxRequestLength of machine config file.

There is a maxRequestLength limit in the machine.config file (look for the <system.web> section),
in the httpRuntime settings that you need to alter/raise if you want to accept anything larger than 4Mb.
These are the standard settings for the httpRuntime:

<httpRuntime executionTimeout="90" maxRequestLength="4096"
useFullyQualifiedRedirectUrl="false" minFreeThreads="8"
minLocalRequestFreeThreads="4" appRequestQueueLimit="100"/>