After some post replies, I suggested to my customer to enable AVX support on that vm and everything was solved.
Now I have a similar issue with the same software on another customer that have a free version of ESXi. Looking for a solution in Google, I found some posts that suggest to enable vMotion, AVX, EVC. The problem is that to enable them it seems to be necessary vSphere or vCenter, but to download these tools you need to have a paid version and the free version of ESXi in not enough.
So, now I'm a little bit confused because I don't understand if the solution to my issue is enable vMotion, AVX, EVC and how can I do that with a free version of ESXi.