That really depends on a bunch of things, off the top of my head, 3 big ones are,
Valve overlap, how many degrees the intake and exhaust valves open at the same time. Smaller overlap,smoother idling.
How your exhaust port and exhaust system flows. The second the exhaust valve opens, exhaust is super sonic till about.1-.15 lift. Better flow, smoother idle.
The better the exhaust scavenges and the less reversion, smoother idle.
