Step 1:
Lower Your Graphics Settings
One of the easiest ways to improve your game's performance is to lower your graphics settings. This can be done from within the game's settings menu.
In general, lowering settings such as texture quality, shadow quality, and anti-aliasing can significantly improve your FPS and reduce input lag.
It's also recommended to keep multicore rendering enabled, as this can improve performance on systems with multiple CPU cores.

Step 2:
Disable Panorama
Panorama is the new user interface for CS:GO. While it looks sleek and modern, it can be a resource hog, especially on older systems.
Disabling Panorama can be done by navigating to the following directory on your computer:
"C:\Program Files (x86)\Steam\steamapps\common\Counter-Strike Global Offensive\csgo\panorama".
Once there, rename the "fonts" folder to "fonts1" and the "videos" folder to "videos1".

Step 3:
-novid -nojoy -high +fps_max 300 -tickrate 128 -heapsize 8388608 -freq 144 +r_dynamic 0 +exec autoexec.cfg
(-heapsize 8388608 is 8gb if u have more change to yours, this limits your ram)
(+exec autoexec.cfg - Download[drive.google.com]) - This disables some commands ingame to boost fps, put it on "C:\Program Files (x86)\Steam\steamapps\common\Counter-Strike Global Offensive\csgo\cfg")