To predict resource and performance loads, it would be helpful to know how MC handles various scenarios -- maybe Matt will enlighten us sometime. For instance:
Are 2 running instances of MC totally separate, therefore use double resources? Or do they use the same program instance but separate data areas, like a browser runs multiple sites via tabs or windows? Is the difference material? How would this compare to the sometimes-requested ability to let MC load multiple libraries for "fast" switching between them?
When a library is loaded, does MC ignore all fields that do not have data, therefore are presumably not being used in that library? This could mean MC avoids the overhead of opening their files (each field is a file). Or maybe better, does MC open only the fields that are in the current view?
And related, what fields does MC open even if not explicitly used by the user/view, such as last-something date and count fields, and what is the overhead of this? If there is notable overhead, can this be managed somehow? (For some uses, last-something dates and counts are meaningless...)
Are some types of fields notably more efficient than others? What is the impact of one long field vs. the same data in multiple shorter fields? (My Keywords field has many values, so the pick list is quite long, and sometimes so is the data of a particular record; works for my needs, but I've wondered if splitting it up logically would be productive.)
How does MC handle abandoned and "white" database space? Classic databases must be packed/compacted periodically (manually or automatically) to recover the space of deleted data and store variable-length data more efficiently. A larger-than-necessary database can be inefficient, but the packing process will really bog down the system (lots of I/O). Is this a factor in MC?
What is the performance impact of showing cover art, small in a view column, a bit larger in the Tag window, medium in certain view types, large in theater view, etc? How does performance compare when the image is in embedded, or in Folder.jpg, or in a specified folder?
What Options settings materially affect performance?
There are probably lots of other questions (and perhaps some have been answered that I haven't noticed), but these are the kinds of factors I like to understand about a database system so I can use it efficiently.