Tiens j'ai trouvé ça en anglais, je sais pas si tu as besoin d'aide pour le comprendre :
Fix for keyboard/mouse lag
I don't have the source but this has worked for some people.
Go to c:\program files\steam\steamapps\common\payday2
Edit the context.xml file
Find the line that contains
<physics settings="settings/physics_settings" fps="60" physx_effects="hardware" multithreaded="true"/>
Set multitraeded to false
<physics settings="settings/physics_settings" fps="60" physx_effects="hardware" multithreaded="false"/>
Another possibility is for Nvidia users to force "Pre rendered frames" to 0 in the Nvidia control panel
http://forums.steampowered.com/forums/showthread.php?t=2198431
Another possibility is to use FRAPS or DXTORY to cap your FPS to below 60
http://forums.steampowered.com/forums/showthread.php?t=3159011
Another possiblity is to exit Raptr if you have it installed.
http://steamcommunity.com/app/218620/discussions/0/864975632555749187/?tscn=1382919353#c810939351312403132
Source http://steamcommunity.com/app/218620/discussions/0/864975632555749187/