This task is about doing performance optimizations for the stars plugin. This includes especially the sun/moon/planet code that got introduced recently.

• measure how long the total rendering (i.e. the calculations performed + drawing) of sun/moon/planets takes (using QTime::elapsed()). Check how long each part takes.
• Provide a table that lists the timings
• If the whole rendering takes a significant amount of time (> 5ms) then we need to do something about it:
• Create a patch that only recalculates positions for the solarsystem object and creates the  pixmap for the phase of the moon if MarbleClock::timeChanged() gets called.
• Look for further possibilities to optimize the plugin in terms of performance and code refactoring.