If you anticipate large uploads, increase IIS's UploadReadAhead value to enable faster tranfers. UploadReadAhead is an IIS parameter that contains the amount of data that the server will read before passing control to the application. The application is then responsible for reading the rest of the data. The default UploadReadAhead is 48kb.
A high UploadReadAhead will enable faster transfers, but your uploads will utilize more physical memory. If you increase the UploadReadAhead value, increase the amount of RAM on the server as well.
To increase the UploadReadAhead value,
HKEY_LOCAL_MACHINE\ SYSTEM\ CurrentControlSet\
Services\ W3SVC\
Parameters\
UploadReadAhead
If the UploadReadAhead parameter does not exist in your registry, you can add it. To add the parameter,