performance degradation with ifort 15.0.2

Hi,

Previously I built my program with ifort 14.0.1 + impi 4.1. Recently, after switching to ifort 15.0.2 + impi 5.0, my program runs ~30% slower on one SandyBridge core. I keep the compiler options the same: -O2 -xHost -openmp. Anyone observed similar things? Any suggestions? 

Thanks!

Best regards,
   Wentao