Counter-Strike: Global Offensive is a quite old and heavily optimized game. Despite this, not every graphics card provides high FPS when you play it. First of all, we're talking about low-end PCs. But even if you upgrade your PC components, the problem may remain.
For example, you've bought a brand new PC and now you want to make CS:GO run faster at 4K resolution, but it doesn't deliver the in-game performance you need. To boost FPS, you'll have to change the video settings of both Counter-Strike and your GPU. This is a non-trivial task.
When it comes to CS:GO performance, you have 2 options. The first one is to change the graphics settings yourself. Most likely, you'll spend a lot of time trying to achieve good gaming performance. The second option is to boost FPS by optimizing CS:GO with our guide.