When my program run (exe), my CPU = 100 %

I would like to use an other program during my prog run but am not able because de CPU was around 100%.

What can I do for that

My prog make calcul between 30 and 45 minutes. It will be long when I need to use an other app.

Thanks
Redg

add DoEvents statements within your calculation code to allow other programs to get some CPU time.