This is what I tried first but was causing crashes... couldn't find the Compatibility Tab for the other way of doing it.
This command might increase your FPS a lot. Warning: If you're already using Windows Xp don't use this command. Sometimes it could make the game crash (for example if you press Alt+Tab and then reopen it), but it will grant you about 10 fps in cities and 20 fps in the other places. If you encounter this problem, just remove the parameter. This command will make the game run in windows xp compatibility mode.If the game crashes, try lowering the HDR to very low, by starting the game without the parameter, and setting the hdr in the rendering options. Then try to add the -winxp parameter again and start the game. If you encounter any problem and your game doesn't start anymore, just remove it. Also, remember to not change any settings while you're ingame or the game will crash. If you want to change your settings, just exit the game, remove the parameter, run the game, change the settings, exit again and re add -winxp.
If -winxp parameter still makes your game crash, you may try running it in windows xp compatibility mode manually. Go to C:\Program Files (x86)\Steam\SteamApps\common\DayZ, program files x86 if your system is 64 bit. Then locate DayZ.exe, right click on it, Properties, click on the Compatibility Tab, then Run this program in compatibility mode for:, select Windows Xp, and press OK.
But this is what made the real difference... just make sure you count the "0's" as I put one too many in last time and made it hell (super slow).
Max Frames Ahead. This fix will smooth the game, so open DayZ.cfg with the notepad (you can find it in C:\Users\Username\Documents\DayZ), find the lines GPU_MaxFramesAhead=# and GPU_DetectedFramesAhead=# and set them to the same value (between 1 and 4) (GPU_MaxFramesAhead=1/2/3/4 and GPU_DetectedFramesAhead=1/2/3/4).
These settings won't increase your FPS but will give you the feeling as the game is running at higher FPS.
Open the file named YourName (.DAYZPROFILE) located in C:\Users\Username\Documents\DayZ\ with the notepad. Now find the following lines:
sceneComplexity=# - set it to a value between 200000 and 50000 (other values are 1000000, 750000, 250000 but they require a high end cpu), it will draw less elements and reduce CPU load.
viewDistance=# - set it to a value between 1800 and 1200, it reduces the cpu and gpu load.
preferredObjectViewDistance=# - it decreases CPU load, set it to 1000 (or between 800 and 1600);
terrainGrid=# - Set it to one of these values: 50, 25, 12.5, 6.25, 3.125. Higher value = Better FPS, Lower value = lower fps but a better graphic quality. I suggest setting it to 25 or 12.5 for the best performance/quality ratio.
shadowZDistance=# - set it to a value between 100 and 200 (100 is the best for me), reduces gpu and cpu load.