My name is Martin Griffiths and I'm PC Lead on SHIFT 2 Unleashed. I'm going to use this post to give you some background on our engine and what's coming up in the first patch.
SHIFT 2 has a completely new engine which is a deferred, light pre-pass renderer. A basic overview of this rendering method can be found at http://en.wikipedia.org/wiki/Deferred_shading
Our deferred renderer is far from basic though - the rendering team at SMS has about 100 man years of render coding between us, and we used some of the most advanced techniques that are known at this time. We did our best - so it's sometimes disappointing after so many late nights to see flippant remarks, over constructive criticism.
So, this new engine allowed us to do cool things such as the night racing that would have been very difficult with an old style forward renderer. With deferred rendering the lighting stage is separate from the geometry stage(s) and hardware anti-aliasing like MSAA in a basic form won't produce correct results. Solutions to allow us to anti-alias had to be found - we came up with two methods to balance AA processing cost/quality over a wide range of PCs. A very large amount of time was spent on this and while some other developers just choose to do a post-pass edge detection filter we weren't satisfied with that, the 'HIGH" method for example was 3 months of R&D.
There are lots of 'tips' about overriding the AA mode - doing this will produce problems with lighting at edges and will also break other lighting components like Bloom, giving a visual look that we didn't intend. If you prefer the look with a driver over-ride then we've no problem with that - but the graphics team wanted a consistent look and feel, to do the many artists who created the tracks and cars justice.
There has been some confusion that our anti-aliasing uses the CPU - it does not. In the graphics options the 'Normal' mode uses MSAA with a special sampling trick to produce correct results at triangle edges - the 'HIGH' method extends this with a depth based search which requires a GPU with high bandwidth because the shaders are sampling many depth pixels for each pixel in the scene. Any performance issue on particular hardware is down to the characteristics of that GPU - there isn't anything we can do about this without a driver update.
To better balance very high-end CPUs the patch will include a 3rd anti-aliasing method which is CPU based - MLAA. We are working with Intel R&D to add this. On quad-core (and above) systems this will allow AA without any GPU cost and little impact to the frame rate to what you see when running with AA turned off currently. This will also help AMD based quad-core too.
Some people have noted that the game doesn't scale well with SLI/Crossfire - SLI performance scaling doesn't just automagically happen, it requires quite close collaboration with the GPU makers. We've been in regularly contact with NVidia and ATI throughout the development of the game, with their performance teams feeding back on any areas where we could improve, pooling our expertise with theirs. About 6 weeks of programmer time was spent pre-shipping on SLI/Crossfire scaling - we needed another 4 weeks since we went gold because of the complexity of implementing this in such a large engine. Both GPU makers have devoted a lot of time to some complex issues.
So yes, the upcoming patch includes SLI/Crossfire scaling. To give you an example a GTX 295 will go from 48fps to nearly 70fps in 1080p. Also the rendering team found some further optimizations so that normal (non SLI) graphics performance should be 5-10% faster with the patch.
Input lag - we've solved the latency issues reported using some wheels. There was a dead-zone issue and a threading problem introduced very late in development that have been fixed.
Garage screen crashes/CTDs - a fast button press issue that wasn't seen during development is also fixed in the patch.
A black screen issue on starting a race requiring a pause/unpause to fix is also addressed. This was caused by a timing difference with the protection system.
NVision - some reverse/double stereo issues with the mirrors and environment maps have been addressed in the patch. NVidia very kindly provided us with more hardware for the render team to address this - Kudos to them for that.
There are also some more minor fixes in the patch - the above represent the vast majority. If you have any specific questions, please feel free to ask in this thread and I'll do my best to reply.
Martin Griffiths, PC Lead, SHIFT 2 Unleashed, Slightly Mad Studios.