The output from the
first pass will be
discarded anyway, so using
slower settings in the
first pass is pointless
The one and only thing from the
first pass that will survive and is going to be re-used is the "stats" file! All settings that don't effect the "stats" can be lowered safely in order to speed up the
first pass!
The final video file that you are going to keep is generated only in the
second pass. That's why using slower settings in the
second pass (and thus faster settings in the
first one) does makes sense.
(And, as explained before, all this happens automatically in x264, so you don't need to take care of it. Simply use the
same Preset for
both passes!)