The problems with net-code in CS:S
There's a very developed and rather old thread going on in the Steam Forums regarding net-code problems found within the Counter-Strike Source engine. It's a super informative read, especially for anyone looking to improve their network performance in Counter-Strike Source.
Here's a quick excerpt from the article:
"I posted this thread, because I want Valve to recognize, that many Gamers are dissatisfied with the current situation. This thread is not mentioned to show how the net-code work or how the net-code should work. The point is that Valve has to recognize the problem with the net-code and to fix it! This thread is for all the cyber-athletes that see CS:S as a sport and matching each other on tournaments and leagues. The game is because of the current net-code-bugs NOT competitive!"
Now i won't say that Valve will never fix this bug, but I'm not going to hold my breath. As i said before, this is an old article, but is definitely still worth a read.
Check it out this thread regarding network performance problems.