Do not try to disable those processes in your screenshot, if you disable Defender, if you do not have another anti-virus installed you will leave your PC open to being infected with malware, the only correct method to disable Defender is to install a 3rd party anti-virus.
If you only have 4GB of RAM on your PC, that is not enough RAM for Windows 11, Windows 11 by itself will use 4GB - 5GB of RAM for the operating system alone, and what happens then is Windows will be constantly accessing the drive on your PC for virtual memory and that will slow your PC down and over time may wear out the drive.
A minimum of 8GB of RAM is required for Windows 11, so really the only solution would be to upgrade your RAM from 4GB to at least 8GB of RAM