I'm currently running Manjaro with i3wm on a laptop with a core 2 duo. It came with a couple of simple conky widgets enabled by default and those probably took 5-10 seconds to load. Just boxes, one with static text and the other with load statistics. Resizing windows is a little painful, as is opening them.

I3 runs reasonably well, but Gnome would probably be too heavy to make for an enjoyable experience.