I'm using v 0.9.6 and I'm finding that animated translations with Affine transition work smoothly but Composite is jerky.

Does anyone know if that was expected in v 0.9.6 and has that been fixed in a later version?

I can make a short video to show the difference if anyone wants to see it but for now I'm presuming it's a known problem.

That is as very very very old version you are using. Please update to the latest version of Kdenlive, here is some info on how to get it: https://kdenlive.org/download/