May I ask what Operating System you are running?
If you are using Windows 7/10 than press the start menu and search "performance".
In the result there should be one that says "Adjust the appearance and performance of windows"
In the menu that opens click "Adjust for best performance". You may also wish to switch to the Windows Classic theme in Personalize.
Please post your PC specs. We cannot help you unless we know what hardware you are using. Trying to run windows 10/8.1/8/7 on a pentium 4 will give you a slow performance while running the same on an i7 can also give you a slow performance due to various reasons . So please do post the specs of your PC.
Laptops upgradability is usually limited, you can throw more ram to it and perhaps a faster drive like SSD. CPU is not upgradable, graphic is not upgradable. You may start by re-installing OS and Apps from scratch, that usually get rid of cruds you have accumulated, free, just time. Have to re-configure all your personal settings am afraid.