Getting top performance out of your computer is definitely a Lifehacker challenge. We've got some ideas for you that may help.
Perform Basic Maintenance
We guess that you're already doing basic maintenance for your computer. But just in case, here are our recommendations for maintaining your Windows PC, Mac or Linux system. Performing those maintenance steps, such as keeping your operating system and applications up to date and cleaning out temporary files, should keep your system running well. Sometimes, just deleting bloatware can really make a big difference in your computer's performance (we recommend PC Decrapifier for the job). So definitely the first thing we'd recommend is to check the guide for your operating system.
Download and Run Diagnostic Tools Like Soluto to Identify Problems
If your computer is experiencing problems, however, like applications freezing or serious slowdowns, you can use computer diagnostic software to troubleshoot the problem.
Previously mentioned Soluto is a free Windows tool that shows you which applications may be slowing your system down. It's also a fantastic tool for magically solving application crashes before they happen and can report crash information based on other Soluto users' experiences.
For other diagnostic tools, you can find Lifehacker readers' five favourite diagnostic tools here. A tool that's not on that list but still may be a great option for you for its excellent interface and benchmarking tools is the previously mentioned free Windows program Fresh Diagnose.
Finally, if you're interested, doing a stress test of your hardware can help you troubleshoot any problems you're having.
Perform a Quick System Check Up Online with PC PitStop OverDrive
If you just want a quick PC health check, however, there's a free online tool called OverDrive from PC PitStop you can use that will analyse your computer's hardware, software, security, and so on, and give you recommended fixes, if any. The site looks spammy, but the tool actually does a good job of analysing your system and can also be used for benchmarking your computer. (Note: PC PitStop also offers PC Matic and other software downloads that can check your computer's performance, but you don't need to download and install any software to run the OverDrive tests.)
To use the Windows-only tool, you have to visit http://pcpitstop.com/betapit using Internet Explorer running in Administrator mode (right-click on IE and choose to run as Administrator). Allow the browser to install the Active-X object, and the site will start scanning your system.
When it's done scanning, OverDrive will suggest fixes like clearing your cache, updating any missing drivers, increasing security settings and so forth. Re-run the tests after making any suggested fixes and you should see your rank improve and your PC operating at least a bit better.
Good luck and have fun testing your system!
P.S. If you know of another great tool for this job, please let us know in the comments.