Ah. Of course. I didn't consider that possibility. Now I've tried back/forward while connected to the internet and looking at Network Usage in Activity Monitor.

Ah. Of course. I didn't consider that possibility. Now I've tried back/forward while connected to the internet and looking at Network Usage in Activity Monitor. I noticed that most of the times when I hit back/forward, there was no network traffic. I expect most of the traffic I did notice was either due to cache refreshes or due to other apps(probably mostly Thunderbird) I have running.