It’s also difficult because of the difference between just having the plugin loaded, and actively playing it. Some plugins add a surprising amount of load even without playing it, whereas others are virtually transparent. Also there’s the spikiness - a plugin that adds a fairly constant load is a lot easier to work with than one that periodically causes huge load spikes.
So perhaps just a broad, subjective scale could be useful - something like:
- Light - only affects the load indicator by a few percent
- Medium - not too bad, but you probably would want to be careful running multiple instances
- Heavy - you might have trouble with it, even if you’re not running much else
I would think that would be useful even across different people’s systems. Ultimately all we really care about is, “Am I going to run into trouble using this?”.