Comment 84 for bug 109943

I have already tested that.

* Only throbber: ~15-20% CPU usage
* Only progress bar: ~15-20% CPU usage
* Both throbber and progress bar: ~15-20% CPU usage
* Both disabled: no CPU usage

@Gunter: I measured CPU usage on Linux with `htop`, where the percentage is always relative to 1 core. 15% means 15% of 1 core. Using full 2 cores would show up as 200%.

> 100% of one CPU normally doesn't indicate that something is amiss: The CPU could be asleep 99% of the time and be busy 1% of the remaining time.

I don't understand this sentence. If the CPU is asleep 99% of the time, CPU usage in `htop` should show up as roughly 1%, not 100%.