This checklist is designed to be a quick overview of steps you can do relatively quickly to improve the speed of running Windows. It's not a guide to speeding up the boot up or restart times. It's also not a guide to removing viruses, malware, ransomeware, etc.
If your Windows 7 PC is running slow but otherwise healthy, this checklist is a few things you can do to try to speed it up with relatively low risk of messing up your computer. That said, BACKUP your computer before doing anything in this checklist.
Microsoft sets an end date for when they'll stop making security updates to a version of Windows, according to Microsoft's official website, you can get updates for Windows 7 until January 14, 2020. After that, you'll be on your own for security. Even so, you should still be using security software in addition to getting updates from Microsoft.
Microsoft encourages you to buy a new laptop or PC to get Windows 10 instead of buying a copy of the software to install yourself. If you're building your own PC (I've got a checklist for the pc parts for that) you'll still have to buy a copy of Windows 10.
So the simple answer is this, until January 14, 2020, you won't have to upgrade.
One of the first things to do is to do a virus scan of your whole system. This checklist for making Windows faster is geared towards "healthy" computers that have already been checked for viruses. There are plenty of guides to picking a security software so I'm not going to make a new one here for you. Some is free and some has a yearly license fee.
After you've checked for viruses, start going through the Making Windows 7 Faster Checklist!
The original Make Windows Faster guide was written for Windows 95 and Windows 98. It's archived here.