I only recently noticed that users who had been away for a few weeks who were trying to get back in to this course (Using Moodle) were having the course page become very slow and sometimes never finish loading!
The problem was too much data to process when creating the Recent Activity display (lots of things happening in this course!) which overwhelmed the way I was doing it (it wasn't very scalable). I've just implemented a new method which appears to give roughly the same speed for small courses, but also gives decent performance on large courses too. Yay!
martin are you saying this could be happening to my site as well because it is a serious problem the pages are not loading and i don't have a clue as to why? except that my server is running with a 256K upload connection. but 1. 5 mb download but i only have about 5 users at on time and dont understand why the pages are not loading.