Hi,
Thanks Bird Fan, ghostmaster and tommie.
No, they're not having any other problems. I was just trying to make sure that I'd done everything I possibly could to reduce latency issues. It does seem to be behaving exactly as you've described, which I guess is good!
So here's a follow up question. If I have advertisements and ad downloading blocked in Mozilla, does the proxy still actually download all that stuff, then my machine just "loses" it on the local request to the modem? I suppose I could contrive some sort of test for that, you can time things with 500ms latency with a stop watch