jtamate added a comment.
I've found the problem. The problem is qSort itself.
Chaning qSort to qStableSort I've got normal times in the test case, select
50.000 files and pressing Shift+Supr.
Also in the small test, the times, running under callgrind are:
qSort: between 33148 and 45745
std::sort between 53231 and 66780
qStableSort: between 11232 and 15116
std::stable_sort: between 22581 and 25957
Therefore, before patching, should I change all of them to std::sort or
std::stable_sort or qStableSort?
To: jtamate, #frameworks, dfaure, markg
Cc: markg, apol, michaelh