http://en.wikipedia.org/wiki/Protocol_header_encrypt

Some ISP use P-Cube/Cisco routers to slowdown/throttle Bittorrent Traffic by examining each packets.

There is a new open "Protocol Encryption" / PE standard to avoid this problem and may increase the bittorrent speed.
This new protocol use "End to End Encryption" to avoid detection by P-Cube / Cisco routers.

New Bittorrent clients with PE:
Azureus (for Linux, Windows).
Bitcomet (Windows Only).
uTorrent:

http://www.slyck.com/news.php?story=1083

Based on my experience:
Unfortunately there were several incompatible, old PE standards and the bittorrent download may get stuck because the client use different standards.

Is there any user who get additional download speed after using the new PE enabled Bittorrent clients?