web performance of a B2B server

I want to know the web performance of a B2B server.
How many Http requests per second or minute can the B2B server process?

It slows down when getting too many XML documents.

Another thing, we are receiving documents from two B2B partners.
How’s different between via one port(e.g. 5555) and two ports(e.g. 5555 and 5556)
when we receiving docs from two partners?

Can we get better performance when we use two ports? or the same thing?

Also, have you ever heard the sync and asynchronous HTTP transport?
Which method does the B2B server use?

Thank you in advance.