How do you know that it's network not your program?

>
>One months ago I completed an install of windows server 2008 r2 for a company of
>about 20 client using windows xp, visto and windows 7.
>
>At the first the significance issues is index corruption. I solved this problem by setting SMB2 to 0
>
>Now I have another big issue. Visual Foxpro program ran very slowly on this network.
>
>How can I solve this problem.
>
>Thanks in advance