Question on router to router communication

[Michael_google gmail_Gersten]

I've noticed that my tor configured as a client will only have one
outgoing TCP connection to an entry node, no matter how many circuits
Vidalia shows as going to that entry guard.

I'm assuming that this continues on other router to router channels --
if there are three circuits that go from (for example) desync to
Tonga, there will only be one TCP connection.

Is this necessary from a security standpoint? Tor can be sped up if
that "one channel per pair" restriction can be broken.

(Just like IP itself. A layer two connection between two nodes has (I
forget exactly) 8 channels, each of which can only have one
outstanding packet. Allowing Tor to have multiple channels between two
nodes will prevent a single stopped TCP from stopping all traffic
going that way.)