Replace the gcc by icc, but meet performance problem

Hi, all,

Now our team try to use the icc replace gcc which we have used years. But find the icc compiled executable file performance is bad than gcc.

We use the script generated some small demos to test this, all in the attached test.tar.gz

Test machine CPU: Intel(R) Xeon(R) CPU E7-4850 v2 @ 2.30GHz
OS: Centos 6.6
GCC: 4.7.2
ICC: parallel_studio_xe_2015_update3

In the test.tar.gz, contains N10, N50, N100, N250, N500 folders, in each folder, contains f10A.c file, which is auto generated by genf2A.pl, then make to generate f10Agcc and f10Aicc, use run.csh to run them and compare the result.

At last, the result is as below:

                GCC      ICC
N10        0.384     0.291
N50        2.107     2.155 
N100      5.429     5.648
N250      15.397     23.575
N500      38.949     58.672 

When N<100, the icc is better than gcc, but when N>100, especially N=500, the icc performance is much worse than gcc.

How can we improve the icc performance? Maybe add some special compiling options?
Anyone know please tell me, thanks very much!