I am building a webpart that includes a function with an SPList as one argument. The list being passed will grow over time which makes me concerned about a scalability issue. Should I worry about potential performance issues using this method?
If you can offer any insight on other SharePoint objects (SPSite, etc) pertaining to my question or provide a link to further reading on this topic, I would be very appreciative!
Why would this be a problem? Do you expect the data in the list will be copied when you call the function? It won't be. SPList is a reference to an SPList object, and you'd only be copying the reference.
Otherwise, I can't think why there would be a scalability problem. Please indicate why you think there might be one.