CPU profiles
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- bottom-up view:

  - shows at the top of the hierarchy function calls with high self
    CPU time (by default ordered by self CPU time)

  - the tree below a top node is the call stack leading to that
    function

  - apparently, the "Self" and "Total" columns are meaningful for the
    toplevel tree nodes only, and are just repeated for child tree
    nodes

  - the (program) is the whole running time from start to stop of the
    CPU profiler?

  - no "count" column?