(Click for general game info.)
Latest drivers: (as at 21/12/2017)
Intel: Depends on your processor; download the driver update utility
Tips and tricks:
Various CPU/GPU benchmarks and data: See this GameGPU article. Additionally, this companion article compares Mantle and DX11 on AMD GPUs.
Note: The articles are in Russian, but the data is presented via graphs.
Cap the framerate/potentially improve frametimes: Download RivaTuner Statistics Server, input your desired framerate limit in the "Framerate limit" box, and hit enter (the program comes bundled with MSI Afterburner and earlier versions of EVGA PrecisionX). Alternatively, those with an Nvidia GPU have the option of Nvidia Inspector, which can also be used to impose a framerate cap, either in a similar manner to RTSS or by way of forcing a different vsync interval (click the small tool icon to open the game profile section).
Note: Useful if you your system can't maintain, say, 60fps and you're sensitive to the wild fluctuations, or you're experiencing uneven frametimes. The greater window the engine has to render a given frame, if you're imposing a lower framerate than the game can otherwise provide, may also help in alleviating stuttering related to data streaming.
Stop the game from crashing after 15 minutes on touch-capable systems running Windows 10: Open the task manager, switch to the Services tab and disable TabletInputService.
Mitigate stuttering: Use the 32-bit executable rather than the 64-bit one. (Credit to ambientmystic.)
Note: So that you're launching the 32-bit executable through Steam directly, navigate to SteamApps\common\Thief\Binaries\Win64, rename Shipping-ThiefGame.exe to Shipping-ThiefGame.exe.64, and copy into the folder the executable from SteamApps\common\Thief\Binaries\Win32. Do note, however, that any patches will replace the executables and so this step will, if the stuttering persists, need to be repeated post-update.
As with Tomb Raider, unchecking Exclusive Fullscreen means you're running the game in borderless windowed mode. Vsync support is in the form of double and triple-buffering.
Presets: Very Low; Low; Normal; High; Very High; Custom
Texture quality: Very Low; Low; Normal; High; Very High
Shadow quality: Low; Normal; High; Very High
Depth-of-field quality: Normal/High
Texture filtering quality: Trilinear; Default (2x AF?); 4x AF; 8x AF; 16x AF
SSAA: Low (2x?)/High (4x?)
2600K @ 4.6GHz
2x overclocked 2GB 670s (335.23)
1680x1050, vsync off
Texture Quality: Very High
Shadow Quality: Very High
Depth-of-Field Quality: High
Texture Filtering Quality: 8x AF
Relative differences (enabled versus disabled):
Minimum: +6.7fps (+~18%)
Average: +13.8fps (+~26%)
Maximum: +48.3fps (+~70%)
SLI scaling could be better. Performance is okay, though, so I'll play while waiting for Nvidia to release new betas.
Edit: Updated results to reflect 335.23 drivers.