I RAN THIEF through 64bit launcher the was lagging like hell i changed graphics settings to very low except resolution which is 1600x900 then game was still lagging then i launched through 32 bit launcher.The game was running so much fine that i was able to increase the texture to high,shadow to high,turned FXAA on.The question is why thief was running so much slow with 64 bit launcher.MY SPECS ARE i3 540,4gb ram,HD 5550 DDR3 128bit 1GB vram