LabVIEW Class VIs Load Slowly While Editing in TestStand

Updated Aug 22, 2023

Reported In


  • TestStand 2016 SP1
  • TestStand 2016
  • TestStand 2014 SP1

Issue Details

I have LabVIEW VIs that are part of a LabVIEW class and I use the "Class Member Call" option when loading a LabVIEW code module in TestStand. Whenever I am editing a sequence which includes steps that call such VIs I notice that TestStand takes a few seconds to load each VI when I click on the step. Is there a way to reduce the load time for these VIs?


When working with large LabVIEW classes, TestStand can take longer to load all the VIs because TestStand will load the entire class when calling a member VI. Therefore if you have a class that contains many member VIs, the load time can increase. The following steps may help reducing the load time of such VIs:
  • Load the LabVIEW class with the LabVIEW Development System while working on the sequence which calls its members in TestStand. You can do so by opening the project that contains the class, right-clicking on the class and choosing Open. This will open the LabVIEW library that contains the class. Otherwise, you can open the .lvclass file from a file explorer or navigate to it within LabVIEW. This will have the greatest impact on reducing the load time.
  • Mass Compile¬†all VIs in LabVIEW to avoid any recompilation when working with them in TestStand.
  • If you are using "custom" sorting in your LabVIEW project that contains the LabVIEW VI and class, change the sorting to the other options such as "Name." The "Custom" option affects your files on disk, where as the other sort options do not. Changing your sort order can reduce the amount of time that LabVIEW requires to load the project. For more information on how to do this, please look at Sorting Items in a Project.
  • If possible, reduce the amount of members in the class.
This behavior has been improved, but not eliminated in TestStand 2016 SP1.

Additional Information

For more information about the Mass Compile process refer to What Does Mass Compile Do in LabVIEW? page.
For more information on how to improve test execution performance refer to Best Practices for Improving NI TestStand System Performance.