Well there are many steps that you can take, not a guaranteed fix though but has partially worked for most.
Change WorkerThreads = 4 to WorkerThreads = 2 in your config.ini file can help your I5 processor (In the game folder, commonly located here, C:\Program Files (x86)\Steam\steamapps\common\Call of Duty Black Ops III\players\config.ini).
Also for stuttering errors ; Go to your config.ini file inside of your Steam folder and set VideoMemory as follows:
//Fraction of video memory usage to target
VideoMemory = “0.75” // 0.75 to 1
Also put Vsync on, and set it below your monitors refresh rate, as in if it's 60hz, make it 58. Disable Dynamic Shadows in game. and also be sure to turn off anything memory intensive while playing it. do not keep 10 tabs open while playing the game, and also close your anti virus during the duration.
And lastly make sure you have the newest game patch and also that your gpu's driver is updated. lemme know if it worked or did not.