Esteemed programmer and computer security advocate Steve Gibson has been doing his thing as the Gibson Research Corporation since 1985. I've personally made great use of his SpinRite disk repair software. Gibson's latest app, InSpectre, is decidedly more topical. This tiny free app for Windows can analyze your machine and determine whether you're vulnerable to the Meltdown and Spectre security flaws.
InSpectre is less than an eighth of a megabyte, and it's a free download from Gibson Research's website. The app will briefly scan your system to determine if you're vulnerable to either of the exploits and then offer a brief explanation of why. It also will tell you if your PC's performance has been significantly impeded by the fixes for those flaws. If you run InSpectre with administrative permissions, you can use it to toggle the fixes on and off—although doing so requires a system reboot each time.
This app is incredibly handy for anyone who wants to study the performance implications of the patches on their system. It's also useful for slightly-paranoid folks who want to make sure they're protected against the newest CPU-related security holes. You can head to Gibson Research's website to grab InSpectre, although you'll need to use a non-Microsoft browser as the app is flagged as malware by Windows SmartScreen. Chrome, Firefox, Opera, and other browsers shouldn't have an issue, though.