There are a number of things that can be done to make your computer work faster. I am going to describe several things everyone can do that can improve the speed. I am not going to describe items that could damage your machine such as speeding up the clock.
The first is to clean your machine. Open up the case if a desktop (with the power disconnected) and use a can of pressurized air to clean the dust out. Don’t hold the can pointing to one location long as you can cause moisture and ice to appear that can damage the PC. If it is a laptop take the can of air and spray each of the openings in the case to remove dust. Dust will cause reduced air circulation which causes heat which slows your machine.
Next in cleaning remove all the un-needed items on the disk drive. You can use a program to clean such as CCleaner (which is free) or System Mechanic (which is sold) or the disk cleaner built in Windows (right click the drive in Explorer which is found by clicking Computer in Start) and also by looking at files in Documents to remove ones no longer needed and emptying the Recycle Bin. Then choose Tools and choose Disk Cleaner. The next is to clean the registry (the part of Windows that knows what all Windows has and all the pieces needed to help run programs. You can use ccleaner (free at ccleaner.com) or buy System Mechanic or there are other programs too. Just do not use or install a program that may pop up saying it can clean your machine or wants installed because it found problems. Most of these are malware and mess up the machine.
Second look at the disk drive in Computer from the Start menu and see what size it is and how much space is used. If you are using more than 80% the computer may be bogging down trying to find space to put your stuff as it works. A larger hard drive will help speed it up.
Third adding memory to the computer can increase speed also. The more memory the more things the computer can do at a time. The memory is where the computer does its holding of things it is working on right now. The memory is like your memory space in your brain. The hard drive is used mainly to store things long term like us writing on a paper.
Thanks Rosie for the question