On Fri, Feb 13 2015, Lars Ingebrigtsen wrote:

> Could you `M-x debug-on-entry RET gnus-sort-threads RET' and then save
> the value of the `threads' variable when this is slow and when this is
> fast.
>
> And then either compare the values to see whether they're really the
> same, or post them here for inspection...

Hi Lars,

They are the same. Please find attached an example.

-- 
           Peter