In developing some group shapes earlier, I have just used the rounded rectangle shape from the basic shapes stencil as a subshape. In some diagrams this shape is used more than 2000+ times as a subshape on a single page.
Now looking at this shape in more detail, I see rather than being a 'basic shape' in the shapesheet this is quite the complicated shape! (see screenshot).
Just using a rectangle created from the home ribbon then setting the rounding size creates a much simpler shape from what I see in the shapesheet.
Does using the complicated basic stencil rounded rectangle shape cost significant performance in diagrams with 1000+ shapes or does it really not matter?
a blog entry from 15 years ago mentioned the Master Benefits (https://techcommunity.microsoft.com/t5/visio-blogs-archive/master-benefits/ba-p/237278).
Thank you Surrogate I have given the Master -> Shape instance inheritance relationship very little thought so far, but yes this must save memory and hopefully some performance as well.
Currently in code I am always dropping shapes from a 'regular' stencil and not from the document stencil, but if I drop from the document stencil then I can change that master to update all shape instances on the page at once.