Hi @Graeme Mahoney
Thanks for sharing the update here.
By the way, since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others.", and according to the scenario introduced here: Answering your own questions on Microsoft Q&A, I would make a brief summary of this thread:
Issue Symptom:
If an Excel program which use vba is launched from a network drive, the program works as expected. But on the local C Drive, the same code takes about 10 times longer.
This issue occurs with different machines with different Windows system and Office.
Current Status:
This issue is fixed via adding the directory location to the Trusted Locations in Trust Center.
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