Slow Editor Performance with Large LabVIEW Projects Containing Many Classes

Updated May 14, 2019

Issue Details

I have a large LabVIEW project that contains a lot of classes, and I see long delays in the editor when I try to make changes in the project, such as creating new class methods. What can I do to improve performance?


When a LabVIEW class is loaded into memory, its entire class hierarchy is also loaded. LabVIEW classes maintain a mutation history which can grow large, especially if classes have large data sets in their private data cluster. If you are experiencing poor editor performance when working with classes, you can clear the mutation history for the classes in your project to improve the editor performance. There is a VI located at <LabVIEW>/vi.lib/Utility/EditLVLibs\LVClass called Set Mutation that can be used to clear the mutation history:

There is a detailed explanation of mutation history in Preserving LabVIEW Class Data. This document also explains how to clear the mutation history of a class by editing the .lvclassfile.

Caveats: If you clear the mutation history you will no longer be able to unflatten objects that were flattened as an earlier version of the class. VIs that were not in memory and contain constant objects on the block diagram which were created with a previous version of the class will revert to default data.