The timer on this page ticks every second. A label on the page does get modified to show how many requests have been made since starting.

With this test, memory usage initally increases as expected. Eventually, the increase starts to taper off. You can see several requests go by with no increase and sometimes even small decreases in memory usage.

Unfortunately, the increases are bigger and more frequent than the decreases which, to be perfectly honest, scares me.

It's possible that IE has some sort of garbage collection process going on here and it doesn't reclaim memory until a certain threshold is reached.