Indeed the 4.12 is slower, though 19% sounds a bit too much to me.
It is meant to fix a problem that is described e.g. here, that is related to the invalid results as returned by the previous 4.56 Beta App. I was pretty sure that the new setup of the S5R1 run would ged rid of this, but obviously I was wrong.
So for the moment we switched back to older code until I find some fix for the faster code that avoids these errors without slowing it down too much. I think that invalid results get more annoying with the now longer WUs.
BM

4.12 PPC app way slower
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I made a new App that should solve the problem while still preserving the speed of the old 4.06 App. However for a first test, this only runs on G5 with MacOS 10.4. Read about it here.
BM
BM