Caching destroys benchmarking

[eluser]tobefound[/eluser]
In the userguide for Web Page Caching it says:

"Note: The Benchmark tag is not cached so you can still view your page load speed when caching is enabled."

However, when I turn page caching on (and at the same timing having set $this->output->enable_profiler(TRUE)), the benchmarking info disappears at next reload.

/T