Advanced Systemcare 8.4 (and newer versions) are excellent at finding problems with programs, registry errors, disk fragmentation, internet connection issues, and many others. I use the "paid" PRO version as I found it not expensive for the benefits you get, but even the "free" version (yes, it really IS free), while not as robust, will definitely find and correct many problems and speed up the overall capabilites of your computer. As it specifically relates to this article, the IOBIT Uninstaller is very good at showing all programs installed on your computer (by the user) and also "add-ons" (toolbars and plug-ins) that sometimes come bundled with other software that you don't want or need, and can uninstall them quickly and easily. Additionally, the Iobit Uninstaller goes much deeper than the built-in Windows Uninstall program to get rid of a lot of the "bloat" that Windows does NOT uninstall when you try to delete a program from your computer. (look for the "Deep Scan" checkmark). Another important program it gives you is "Startup Manager", which allows you to actually view all user-installed startup items, their effect on boot time, resources used (%), name of the manufacturer, and the ability for the user to Stop, Delay, or Delete the item. For inexperienced users there is even a "1-click" Optimization button to speed up startup. While I highly recommend this product, I am not associated with the company in any way, I just really like it. That being said, you cannot rely on it alone. You MUST be proactive about keeping "drive-by" programs from downloading onto your computer, so you simply MUST have a good, robust anti-virus, and a good anti-malware program. Again, I use the paid versions, but I believe you get what you pay for. I also strongly recommend MalwareBytes (paid version) as it includes a very good anti-exploit capabilty that prevents most known malware from even downloading. (well, unless maybe from Chinese government hackers..) The major benefit of the paid version is it "auto-updates" the database to keep the program current on startup.
Back to Windows only interactions, if you are comfortable with using DOS, you can try using "msconfig" in the Windows "Search Programs and Files" (in Win 7), and then "uncheck" any listing under Services or Startup that you don't wish to have running when the computer boots up. Make sure to make a list of what you uncheck, so that if something doesn't work later as you expected you can return and put a checkmark back in. I would strongly suggest that you do an internet search of each line item you wish to possibly uncheck so as to NOT stop critical processes in Windows itself. (most of the time Winows won't let you stop critical processes anyway, but I simply mention it to make sure you are being careful.
From experience, I can tell you that if you are experiencing a significant computer slowdown when TRYING to do computer maintanence, it is often from programs interfering with each other... specifically, as when you are trying to "Defragment" the computer and your Anti-virus and/or Anti-malware programs are still running. If this happens, you can turn off your anti-virus temporariy, OR (and this is my preference) bring the computer up in Safe Mode, then disable the Anti-virus, anti-malware, and any other large running programs, and THEN run your defrag program. (Some versions of Windows don't allow you to defrag in Safe Mode, but the Advanced Systemcare prog will work)
All of these suggestions take time, patience, and a step-by-step approach best done using a checklist so as to make sure you do all steps, in order, and minimize the chance for mistakes.
I am sure there are other programs out there that will do similar things. I am just very familiar with the ones mentioned, and as a retired network engineer I know new ones come out all the time. Do your own "due-diligence" research on any program you consider using. Be wary of sites that "promote" certain products as they simply might be getting a kickback. Try searching for "reviews" of particlar programs, and don't buy the first you see... take your time. Good luck!