The graphic options for Metro Last Light are the following:
Resolution: change it your native monitor’s resolution. It is much lower by default when you first start the game.
Quality: this has a big impact on your framerate. Set it to normal or high.
SSAA: this is an anti-aliasing setting. It is the most resource consuming setting. Turn it off if you notice any delay when moving the mouse cursor even in the game’s menu.
Texture filtering: you can leave it to 16x, it won’t have a big impact on the framerate.
Motion Blur: turn it low. It is actually a matter of taste, if you like your game blurry or not.
Vsyinc: is related to the monitor’s refresh rate, leave it enabled on any game. It is disabled by default.
Advanced
If your game doesn’t run smooth with the settings turned to maximum, turn SSAA to off and the “Quality” option to high or normal.
Metro Last Light works perfect on my system, I3 – 3 GHz, 8 GB ram DDR 3, ATI Radeon HD 5670 (1 GB RAM, DDR 3), on “normal” quality and with SSAA disabled. It runs smooth even on high “quality” but turning it to “very high” and with SSAA enabled, it just kills my framerate.
Overall, the game is very optimized when it comes to performance and resources.
How is it working on your configuration?