Might be worth switching off V-Sync if you have it activated. I used to see the same 'stutter' at higher settings until I increased my RAM amount. Just the other night I noticed I hadn't seated one of the DIMMs properly (8.00 gig installed, 4.00 gig available), and was seeing very slight stutter on the bridge or external views.
Reseated the RAM so the full 8gig works and the stutter just vanished. This is quite the admission for me as previously I've doubted the significance of RAM amount needed for SH5. I now run all max settings bar shadows and anti-aliasing (half & 2x respectively), and it takes 3.6 gig of quad-core CPU, a 1.3 gig GTX 570 and 8 gig of 1600mhz RAM running at full tilt to give me a solid 60fps with V-Sync on. Anything lower and settings need to drop; textures is the worst culprit and should be (along with AA & shadows) the first settings you decrease if you find TDWs idea doesn't work.
If you have a recent-ish Nvidia card, most of them now support FXAA, which is far less GPU intensive than other AA solutions. You can apply it manually to SH5 in the Nvidia control panel (ensure it's set to override for SH5 only) and see if that helps too - should be a decent 10fps boost.
