[kamocat]

Well, the PID probably isn't your most critical task, so a delay would be good. I would give it a delay of 5 to 25ms.
One thing I may have neglected to tell you:
PID doesn't "just work". You have to tune it.
Luckily, temporary deployments in LabVIEW make that easy. Just create a control for the parameters, and tune until it works. Make sure to start with Proportional, and then tune the others to whatever is appropriate.

EDIT:
Feel free to post your code. An easy way to post your whole project is to zip the folder it is contained in, and just upload the zip as a whole. To make it smaller, you can delete the "Builds" folder first.