Hi,
As o one has answered with an obvious answer (that I don't know of!) I suspect the answer is that an Add-in is part of Project, so hiding Project would also hide the Add-in which wouldn't help.
To speed code up try Application.ScreenUpdating=False
Add-ins do run in a separate process from Project, which is why they are fairly slow and VBA is faster when working with Proejct data.
Rod
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Rod Gill Project Management