The first part of this paper presents an empirical analysis of new transport protocols designed to achieve better performance compared to standard TCP Reno. Investigations are focused on TCP BIC which is already widely used in current Linux kernels. In the second part we discuss the influence of these variants on the throughput of multiple simultaneous connections as implemented in many file transfer applications. With our results we prove that a) alternatives to TCP Reno become applicable today, b) better performance is achievable at the cost of unfairness and c) operating systems relying on TCP Reno may become disadvantaged in the future d) with new TCP variants the use of multiple stream file transfers as implemented in GridFTP is no longer reasonable in many environments. Keywords: High Performance Networking, Congestion Control, TCP BIC, GridFTP, Firewalls