Reusing Material Parameters in Functions causes lag

If you have more than 1 Parameter with the same Name inside a Material everything is fine.
If you have 1 Parameter inside a Function and another Parameter with the same name (regardless if inside another function or just placed as node in the Material) there will be lag - even if the Parameter is not connected to anything!

Expected behavior: adding Multiple parameters with the same name won’t cause lag whether being placed inside a function or not.

I have attached a Project, that contains 3 Materials and corresponding Instances. All instances contain a Vector 3 Parameter. If you open the Instances and modify the Vector 3 by dragging around in the color wheel inside the color picker window, you will notice that Instance 1 and 2 will create a lot of lag, while Instance 3 will be smooth.

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Actually this appears to be fixed in 4.16. I can’t find anything in the release notes but well it seems fixed.