JAbrahamson

A updated steam_api64.dll is the reason for this problem, I replaced that file with an older verison and my backup works again

How to install: 
 
Someone using it:
 
 
 
 
If i remember correctly (havent used EUP in a while), you use skin control to set your character and customize (save it). Then just open eup and set the clothing and open you Rage Console (F4 by default) and type "forceduty" (without quotes) and you will be on duty with your character.
I had trouble loading my online character with rage so I started the game without Rage and loaded into directors mode and loaded my online character. I saved him using skin control and then restarted with rage. Open skin control and load your online character, then open EUP and set you outfit and then open the console and force duty and you should be all good!

How to install: 
 
Someone using it:
 
 
 
 
If i remember correctly (havent used EUP in a while), you use skin control to set your character and customize (save it). Then just open eup and set the clothing and open you Rage Console (F4 by default) and type "forceduty" (without quotes) and you will be on duty with your character.
I had trouble loading my online character with rage so I started the game without Rage and loaded into directors mode and loaded my online character. I saved him using skin control and then restarted with rage. Open skin control and load your online character, then open EUP and set you outfit and then open the console and force duty and you should be all good!

Solid 60fps, GTX 960, Very High settings, 16GBs RAM. Very very happy versus my old PC.
NVIDIA Control Panel > Manage 3D Settings > GTAV.exe > Shader Cache, turn her off.

If you have Traffic Policer installed take it out and see if it still stutters and lag.

I have mine running on Titan X. At 1080p there's no issue, but I can't run the game at 4k unless I have another TitanX in sli. I have another setup with a GTX 970 and it's almost the same performance at 1080p which is pretty sad.
I noticed if the game is on a regular HDD the performance especially driving is awful, even with the most powerful setup around. Once you install onto an SSD the performance should be noticeably improved especially driving around. This is mostly due to GTA loading and off-loading areas as you drive around.
Also, at one point I had an ENB mod which caused random fps issues when lightbars were on, removing this helped a lot.

Memory leak issues are still a thing, too. Check your RAM usage when your game starts stuttering. If your whole RAM is used, time to reboot the game.

Some people have reported GTA V lagging with the new cards (980-TITAN X). I know for a fact my TITAN X can do GTA at 60fps flawlessly, except it doesn't. try messing around with the settings, that's what i did to somewhat fix mine ( i get the occasional drop to 50-55fps). My guess is Rockstar hasn't fully optimized their game for the Nvidia cards or Nvidia hasn't fully optimized their cards for the game.
If you haven't already, try Razer Cortex and use the Game Booster, this could help with the FPS issue 

Use traffic police mod by albo, then you can use the mimick feature to make them pull over right where you want them.