Hello Eclerc95,
As RavensFan said, the VI itself as well as a better description of the driver VIs you're using (what hardware is this, and where did you get the driver from) would be extremely helpful.
As for a few things that are discernible from the screen capture you provided:
-It looks like you're using something over a serial bus of some sort. Be aware from the get-go that this hardware will not respond "instantly".
-It is possible that the device itself provides a timer function similar to what you are attempting to achieve in software. If so, that will be the fastest approach. Without information on the hardware it's impossible to say, though.
-It appears that you are reinitializing and reconfiguring your hardware each time your main loop executes. If possible you'll want to initialize and release your session outside of your primary loop. Again, information on the driver VIs you're using would help us offer better advice.
-You seem to be sending four separate commands to change channel voltages to the device in (an indeterminate) sequence. Are the driver VIs you're using reentrant? Does the interface provide a way to configure multiple channels at once? If you can cut down on the number of individual commands you need to send the device you may see an improvement in the response time. That is, you should see an improvement in the response time, but that's another question that can't be answered without more information about the device and/or driver you're using.
The good news is that it definitely looks like there should be multiple ways to speed up your application!
Best Regards,