I do think it is the gore mod, and the problem isn't specific to "low end" computers. It's not a normal frame rate issue that passes. I have clearly noticed it builds up and gets worse as maps go by. Ultimately I have to kill the Source engine and restart it.

It feels very much like a memory leak to me. I suspect that some aspect of the gore mod isn't cleaning up after itself, so every one of those deaths leaves garbage that doesn't go away until you restart the game.

In this case, having a high end computer would allow you to go longer before it became a problem, but ultimately the problem would bring it down too.