Laptop is running slow ,memory usage is less how to fix

You don't say what operating system you are using. If it is Windows do a full Antivirus scan.

Settings > Update & Security > Windows Security > Open Windows Security

On the other hand you may just have too many applications loading during the boot-up process and also running in the background once you are booted up.

MSconfig to the rescue:

• To fix click on Start > Run and type msconfig.
• From the menu bar click on Services and look through the list and remove anything that you think unnecessary. If you are not sure don't tick it! Generally any Microsoft service should not be removed.
• Now select Startup and untick any applications or software you don't need loaded at startup.
• Click OK and restart your computer. Does it load faster and now generally run faster? Then that was your problem.
• Now this is a good feature. If you perhaps unticked something you shouldn't have reload msconfig and select General from the menu and click on the circle in front of Normal Startup. This will return everything back to the original settings.