>When Automating Excel, my framework takes care of some details. The one I am concerned about right not is that it will re-use an existing Excel instance, instead of re-opening Excel.
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>Now, I was considering to at change this, or perhaps give the user the option, since re-using Excel may sometimes cause interference. For instance, the user has an open dialog in Excel - and a new spreadsheet can't be opened. Also, Automation seems to be quite a bit faster if Excel is invisible (and only made visible later).
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>My main worry is this: IF I do this proposed change, will it consume much more system resources? Especially RAM, I would guess.
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>TIA,
>
>Hilmar.

Hilmar,
I don't suggest using existing Excel instances but reopening. Using existing instance doesn't only have problem of dialogs. User might be closing excel just at that moment for example which would take away both and cause maybe C..5 errors.
I think it's a myth Excel would be faster if it's invisible. My experience shows it's the reverse.
PS: Creating new instances would use more RAM.
Cetin