then a full Reinstall is the way to go. That way you get a brand new uncluttered system that is fast as the day you got it.
I notice two things in your post, 9 years old and cleaners/accelerators.
9 years old and when was the last time you cleaned inside the case to remove dust bunny build up? What housekeeping have you done on installed apps that you don't need loading at startup, checking running Processes to ensure you don't have any that you don't expect, and trimming down unneeded Services?
Cleaners/Accelerators - Cleaners always worries me. Registry cleaners, System optimizers, and so on rarely improve consistently if at all, and over time the damage they can do to the registry and system settings can run deep. Also security apps change over time and where applications like Spybot with its TeaTimer running may interfere with today's anti-virus, we reconsider having anything other than an AV running real-time and switch to stand-alone manual anti-malware scanners that we run once a week or so.
I never understood the need for accelerators. All they can do is cache web site content but the browser history cache does that anyway. Accelerators cannot increase speed above what the ISP provides.
My own XP Pro Dell Dimension 3500 with 3.3 GHz processor and 2 GB of RAM still runs sweetly after 10 years, but even so it is showing its age. However I treat it with care and attention, keep it clean and reduce the load as much as I can. It will never run as fast again as my newer Win 7 system, but it still gives me a lot of fun.
We know very little about your system and setup, other than it is a PC.
pc runs slow like on dial up ..adsl..512/128 it appears to lag when loading and at times when using some accessories as well. I have noticed if i re-click the mouse it jumps into action a lot quicker ...like its possessed. I have cleaned all, added special software (cleaners/accelerators) and these are not the problem. Last 6 mths from instantaneous to wake me when your loaded most of the time. I stream a lot of video and it's just got to the stage its PI__ING me off bigtime. PC is 9 yrs old. Randomly some days it works like a new one briefly. I am past the usual tweak/clean stage I need to up the game to show it who it's Master is again. wonderful when they work properly isn't it.