"# long time" additions (#12272) needs review

[Jeroen Demeyer]

Could somebody please review ticket #12272:
http://trac.sagemath.org/sage_trac/ticket/12272

It is a very trivial ticket adding "# long time" at various places. I
would like to get this merged in sage-5.0 to bring the ptest time down a
bit. Since it is really just about adding "# long time", I hope the
review can be quick.


Thanks,
Jeroen.