PC very slow to respond

download the free version of following

https://www.piriform.com/ccleaner

and install it and run it.

Registry cleaners, no, don't use.

Try AdwCleaner http://www.bleepingcomputer.com/download/adwcleaner/

See if it finds unwanted stuff.

If it does and after cleaning them out run the free version of MalwareBytes https://www.malwarebytes.org/

You may also consider running MalwareBytes even if AdwCleaner finds nothing.

Clean out all the dust from inside the PC. Make sure the fans all run smoothly and that it isn't overheating.

Besides that it also depends on the hardware and how the PC's are used. If it is an old PC with old hardware, it will be slow compared to modern PC's. If the user has 100's of tabs open in the browser, or if he has a lot of open software, it will also slow down. Crappy AV tools like those from Symantec use a lot of resources. Replace it with something lean and fast, like Panda AV. If the PC is used privately, the free version is very good. Or even the built in m$ AV tool is better than symantec (norton).

My advice is - avoid to use any optimizers, registry cleaner if you can. Usually, in most situations, there's no effect at all, or even you can mess your OS completely.
Check CPU usage. Often Adobe reader 11 even if it is closed hogging CPU at 100%.
Try adwcleaner as it is suggested by dbrunton.
Aside of high CPU usage, how much paging is used (maybe your system don't have enough of RAM), HDD is in bad shape (bad sectors), or AV is blocking your work, your power management is set to power saver etc .....

This PC is a moderate 2.0 ghz w/4gb of ram is currently free of dust and I recently cleaned and replaced thermal paste. I noticed only 1 out of 2 users choke to respond to any click or command.  There's a notification keeps popping up lower right hand (files waiting to be written to CD) could this be my problem. I am researching recommended software thank you. Will respond soon.

You can write to a CD from any folder, so perhaps just put in a CD or DVD and allow the write to occur.

If you see the Windows Explorer folders for the write, delete them.

Here is a discussion in Tom's Hardware to delete the files and cancel the message. They also suggest just burning the files onto a CD / DVD

http://www.tomshardware.com/faq/id-2079075/files-waiting-burned-message-windows.html

First things to look for is average and peak CPU load, and whether the disk is used all the time. Massive Hard drive access can bring down the PC to a halt for seconds.
The above said is all true, too - AV can slow down file access, but should only do for first access (for unchanged files). This one is hard to track down, though, and only switching off AV real-time scanning temporarily can show whether that's the culprit.
If network access is slow, authentication issues might be the cause. The server's security event log might reveal that.

can you list the spec of the computer and the operating system, this is the most important thing in regards to judging performance.

2GHz could be anything from an old, single core Pentium IV, which I'd expect to be slow, up to a newer multi-core CPU.

The write to CD notification should not slow down anything. that's just when files are put in a certain folder, which is meant to be written to CD. If that folder isn't empty, you get that message. If you don't need anything to be written to CD, you can delete the contents of that folder.

The link below shows you how to get to that folder:

http://www.softwareok.com/?seite=faq-Windows-8&faq=109

If you only have performance issues with one user profile on the same PC, I'd just backup important data from that profile, then delete it and create a new profile for that user. After that copy back the important data you backed up. Make sure all the users are logged on as standard users, and that they don't have admin rights.

A further thing, if the user account you have speed issues with is an m$, and not a local account (on Windows 8.x the m$ account is the default), then he will be synchronizing it's data with the m$ OneDrive cloud, and that can slow things down, particularly at login and logoff.

I'm leaning towards John Hurst although I'm looking into those software options. John I like the temp folder and drive cleanup procedure. I like the idea of getting in there and doing the leg work myself as software tends to attack everything in its path, find & fix, I was thinking of creating new users, transferring data to the new user profiles and deleting old user folders. But always have a problem deleting those folders after data transfer, even in safe mode, It's an alternative to a clean install but this > (The action cannot be completed because the folder on a file in it is open in another program) this is the window I get when trying to delete the folder. Any ideas?

To Mark

Standard built PC no brand name
Intel 2 core 2.0 Ghz
4GB Ram
Windows 8

You don't manually delete the folders, but rather delete the user account from the control panel. It should ask you then whether also the data should deleted. Say Yes there. That then deletes the complete user's account.

Thanks John, looking into unlocker,

It's better to consult with an expert try Hotfrog PC Maintenance Showcase

Thanks Rindi, I do delete the user account along with files, however these old folders remain in the users folder and I'm thinking that might affect the system performance

Test memory & HDD test (also consider other hardware tests).
memtest86
Link:
http://www.memtest86.com/

You can use UBCD to use memtest86 & many other hardware testing tools for free.
Link:
https://www.ultimatebootcd.com/download.html

Good morning gentlemen, sorry for the long delay holiday stuff. Ok it seems this system was hit with a nasty virus called "HELP_DECRYPT" copies of these files were found in every folder on the system. Any experience with this?

Have a read of http://www.bleepingcomputer.com/virus-removal/cryptowall-ransomware-information

You really need to know which version of the virus you've got.  

A good anti-virus will get it but most likely all of the data is gone.  You may have an option to recover the data by paying the Bitcoin fee but that doesn't necessarily guarantee you'll be able to recover the data if you do pay.

Consider nuking the hard disk and starting from fresh with a new installation of Windows.  I'm presuming you've got access to the restore media.

Now that you have confirmed a virus , backing up and reinstalling Windows may be the most robust choice.

without knowing - i gave the best advice -

If it is a cryptolocker type virus, then you should nuke the system and do a factory restore, or restore from your backups. The data on the PC is lost and can't be recovered, so you need to restore that from your backups too. If you have data in the cloud, or on the network, that may also be encrypted, so you should check that data to and if it has been encrypted, restore it from your backups.

@GMorris215  - Good luck with the computer.

Thanks John, all's well.