What is the best tool to use to speed up my computer?

To fix it, you must first know what, if anything, is actually wrong with it.

What is it doing or not doing?
Specs of this thing?

Fix it software will barely do anything.

However, you can download CCleaner a program that i personally use and it does a good job at removing unwanted files.
*Do not clean the registry with the program

You can go to the tools section, uninstall the programs that may be bloating your pc.

Additionally, go to the startup tab and disable the programs that you do not want starting up when your windows does.

If your Hardrive is near full capacity you can try deleting your unwanted files by using WinDirStat.

Other than that the only clear way to speed up your computer is to get an upgrade or completely build/get a new PC.

What are your PC specifications? It may be very old and outdated.

It is not just one magic tool but several programs that you need to run Here are some popular free programs. (Do NOT run any type of defrag program on an SSD - SSDs do not need to be defragmented).

PC Decrapifier – Manufacturers often install trial programs and other “extras” on new computers. For the most part, this bloatware just slows down the system until it’s removed.
If you have a new computer, or you never removed the bloatware from your older computer, you can get a quick speed boost by running this program. It automatically detects programs you probably don’t want and uninstalls them quickly.

CCleaner – Anything you do on your computer leaves a trace somewhere. These can be small registry entries, a full browser history or multi-gigabyte temporary files.

Not only do these take up space, they can reveal sensitive information to snoopers. This program cleans out these traces with the click of a button. Plus, it includes a powerful program uninstaller and registry cleaner.

Duplicate Cleaner – Duplicate files may be wasting space on your computer, especially if you have large photo or music collections. Fortunately, you don’t have to go hunting them down yourself.

This program finds and deletes duplicate files in moments. It can even detect files that have the same information but different names.

Defraggler – You may have your files organized in tidy folders, but the underlying file system can still be messy. Parts of files can be scattered all over your computer, which makes your computer sluggish.

Windows has a built-in defragmenting tool to fix this, but it isn’t exactly speedy. This program, on the other hand, defrags your drive quickly. Not only that, it can defragment specific files, so you can select ones you use frequently. Your computer can be running faster in seconds.

Malwarebytes – If you’ve already got good antivirus software, you may think you’ve covered all your bases on computer security. But what you don’t know can hurt you.

This essential add-on will catch the programs and little viruses that slip past your safety nets. It’s a great program to have in addition to your main antivirus software. You can always use another defense against aggressive viruses.

TopWinPrio – When you have lots of programs running and windows open, your computer can really bog down. When you need to speed things up a bit, this prioritizing program does the trick.
You can set TopWinPrio to run the top window on your screen as the priority. This causes the background programs to slow down and boosts your most important task.

Should I Remove It? – Just like everything else, computers can get cluttered with unnoticed items filling up space. When you go to clear space, do you know what’s essential and what can get the boot?

Should I Remove it? It will tell you exactly what those pesky programs do and the percentage of users that deleted them. It’s an easy way to see what programs can stay and which ones need to go.

What are the specs of your computer? I'd start by running CPU-Z to identify the major components, to get an idea how fast it is supposed to run.

In my experience, "cleaning up" your computer with programs like CCleaner is sometimes helpful, but seldom produces any dramatic results. If your computer is getting slow, the top three reasons I can think of are: (a) It's too old to run modern bloatware. (b) it needs more ram. (c) the hard drive is overdue to be replaced.

My dad's notebook was getting painfully slow, so I replaced the 2.5" hard drive with an SSD drive and did a fresh re-installation of Windows 7. The hard-drive was the culprit, the notebook flies now.