TraderGrid CPU utilization up after changing the update rate

The trader grid sample makes 5 updates per 10 ms (500 updates a second). This mode keeps CPU utilization almost at 0. If I change the sample to make 100 updates each 200 ms - CPU stays to 25%. Same number of updates per second, same amount of work to do. Is there an explanation why CPU is going up?

I do not know what the real explanation is, but I suspect it has to do with some kind of flow/work load analysis. It seems that at 5 updates every 10 ms, things flow smoothly. If you move that to 100 updates every 200 ms, you might get queueing problems that slow things down. The point is that the 100 updates all arrive at the same time (more or less). The 100 updates are not equally spaced in the 200ms (which is what 5 updates every 10 ms does (more or less) spaces the work load out).