An i3-5005U is a very slow CPU. If you compare say a very good gaming CPU (like the i9-9900K) versus an i3-5005U, you will see that the i9 is going to be 600-700% more powerful. I say this for you to realize that is the gaming standard today.
The onboard HD GPU you are using is also very slow. The standard GPU today is a RTX 2060 or GTX 1070. The difference in performance against your HD Graphics 5500 is that the GTX 1070 is 1800% faster than your HD 5500.
So in summary, your computer is not meant for gaming against todays standards. Its designed for general computing use.
Even though you can use it to game, adding OBS on top of it to capture will stress it out even more. The types of games you can use it for are lower end FPS types. Not for first person shooters that demand high FPS as its going to stress your computer, let alone be unplayable. You need to be doing at least 60FPS to be competitive and to make your recordings look naturally good. Even 60FPS is on the low end. Most FPS gamers do 144FPS and above these days.
Which brings me to your viewers who will be watching your content. Those that play COD do so at high FPS and expect to watch others playing at high FPS. If they watch your recordings, the fluidity and slowdown is going to be obvious and most likely, few will even watch it.
So I think you know this already. You really need a better computer. I just wanted to say the above to wrap your head around what you are dealing with and not to expect much with your computer.
Here's some suggestions on how you can try to make things a little better:
- Turn down all in game video settings to their lowest. Its not going to make the game look its best but will reduce CPU/GPU load.
- Reduce OBS recording resolution to 16:9 ratio 720p (1280x720) or 480p (854x480) and use Bicubic downscale filter.
- Lower OBS FPS to 24 or 30
- Set OBS Audio sampling rate to the lowest to save some bits - 44.1khz
- Avoid running services and other applications while you play. Its just your game and OBS Studio only.