Computation performance is very slow while using SIMULINK in a computer workstation

I am using MATLAB/SIMULINK 2012a, it has installed in a computer workstation having configuration of Intel®Xeon®CPU ES-2650 v2 @2.60GHz, installed memory-32GB, System type-64bit. I run a SIMULINK model with same MATLAB version in a system of i5 processor with 8GB RAM. It is found that I5 processor has better performance than the high configured workstation. e.g a I5 processor system takes 3 minute to complete 3 second run of SIMULINK model,however, workstation takes 5 minute to compute the same model with same MATLAB version. I have tested many models with different MATLAB version also.In all cases same problem arises. I could not short out is there problem with computer workstation or MATLAB software. please help me in this regard.