good for testing performance with multiple TCP streams.
Siege is an http regression testing and benchmarking utility. It
was designed to let web developers measure the performance of their
code under duress, to see how it will stand up to load on the
internet. Siege supports basic authentication, cookies, HTTP and
HTTPS protocols. It allows the user hit a web server with a
configurable number of concurrent simulated users. Those users place
the webserver "under siege."