The commonest reason of slow PC / laptop is too many browser windows open – in too many browsers. It does not matter if it is IE, Edge, Firefox, Chrome or Safari… all of them are like an operating system! Just close them first. Find out the actual browser pages you want and re-open them. That’s it.
I have just the browsers open. No other apps. Each browser has just ONE site open.
IE = CNN.com, EDGE = Amazon.in, CHROME = YouTube.com, Firefox = portal.office.com
We tend to forget how many sites we have opened in how many browsers! Be mindful of that and you are good to go.