There is in some respects. It's well known that the little Cox engines (actually even their big brothers...if you call a .15 big ) respond very well to high nitro but I suspect that's more to do with design, use a lowish compression and high nitro to get a lot of power. But small engines also have a much larger interior surface area for their swept volume than bigger engines and this area both soaks up heat and gives a larger % of unburnable stagnant mixture. Nitro would help make up for this bit of inefficiency.

Compression by itself though isn't an indicator of how much nitro an engine needs to run. I have an old Fox 35 with 6:1 compression that starts instantly, hot or cold, using no nitro. It doesn't idle though...could be because it hasn't got a throttle .