Performance issues with Kid Chaos OCS/ECS on Intel Atom

[Mequa]

Full system specs here.

While the vast majority of Amiga games (including AGA) run full-speed (50/60fps) on this setup, Kid Chaos struggles to achieve 46fps, no matter how I tweak the settings. (Either set to 50fps, 60fps, 60fps VSync or 99fps... I get the same speed.)
This rises to around 48fps if I disable sound, but still looks noticeably slower than normal.

WinFellow can achieve 200fps for Kid Chaos on the same setup (without sound, very choppy WITH sound, crashes with fullscreen)... but surely 1.6GHz Atom is fast enough for WinUAE (especially for non-AGA games)?


My guess is that the performance issue is related to the custom graphics chipset emulation, given than enabling JIT or disabling sound makes a negligible difference in speed.
This game makes extensive use of parallax scrolling - perhaps the method it uses runs into a bottleneck in WinUAE?

I'm also wondering if anyone else (with legal access to the game of course ) has a similar spec machine they'd like to verify this performance issue with.