Load nodes partially? Is there a way to partially load nodes based on the view mode? Say I've got a lot of fields, but for the list view I need only 3 of them ... node_load fetches them all, which doesn't make sense. Or does it? I think about using computed_fields, but when it comes to larger lists I'm a little concerned about performance.
Check out field_get_items(), or to go a bit more advanced (and more 'meta'), use EntityFieldQuery (see examples here).

But, if you're doing this outside of a loop or something, it's often easiest to do a full node_load(), as you can just grab more fields out of there when you need to (in the future) without having to add a bit more code.

My rule of thumb is this: if I only need to load one or two nodes for a particular operation, and the node doesn't contain more than 10-15 fields, I'll just do node_load(). Much more convenient when you don't need to worry about the extra 50ms or so... (for smaller node objects, of course. It's different if you have a node with 25 fields attached!).

[Edit: Just realized field_get_items() still requires the node object itself... which defeats the purpose.]