Less photons with directional light?!

Hi everyone,

I have a strange issue on my project. As you know we need a very good light quality for archviz. So i changed the typical photon settings in the BaseLightmass.ini. Now back in my scene I use a skylight and a directional light for some nice light effects. If i turn skylight and directional light to STATIC, so both lights should effect lightmass, the collecting photon process on my agents takes about 3 minutes. If I turn directional light to moveable, so it has no effect on lightmass, collecting photons takes about 18 minutes. So 18 minutes was what I expect. But I don’t understand why collecting photons needs less time if i add a static directional light? So what is wrong?

Greets Chris.