There isn’t a good system for this yet but what you can do is use a decimate modifier only enabled in the viewport so that it will render at fully res but it won’t slow down your viewport.
I rigged a character and the shoes were far too complex for my computer to handle.
This tells me something else is going on though – the mesh should have never gotten to that point in the first place if modeled for rigging. Can you share what the model looks like? My initial guess is that most of the geometry is probably not necessary and the shape and performance would both benefit from simplifying and using a subdiv modifier instead.
Hope that helps!
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