If computer goes very slow how to conform that which thing is disturbing and how to correct it?

System slow down due to many reasons such as Virus Infection, RAM capacity does not fulfil requirement of newly installed software or C Drive became full.........

FIRSTLY CLAEN THE HARDDESK  FROM VIRUS by clane , then claen h.d from unnessary file from my computer rihgt click mouse on h.d the clane 

secondly defragment 

First thing would be to disable your wifi/ethernet connection and closing all the unnecessary  then by using CTRL+ALT+DEL (Task Manager) click on the Processes Tab and at the bottom left side of the window you will see a number. That number shouldn't be greater than60.

If it is, that may be one of the main causes for your slow system.

How to correct it:

Windows Key + R

write msconfig

Enter

Go to Startup Tab and disable whatever programs you are not using - Adobe, Office, iTunes and other programs that you are not always using. Remember to double check before saving and restarting. Do not disable any programs that the Operating System is using on a normal basis (Intel USB3.0 Monitor is an example of a program that you should leave enabled) or programs such as Antivirus, mouse/keyboard software, network software etc.

Other things you can do:

- Delete Temporary Files - on windows7 just go to User/AppData/Local/Temp and by using CTRL+A and Shift+DEL then enter (make sure the window is in foreground otherwise you might delete other files). Just press Skip on any files that cannot be deleted.

- Disk Defragmentation - go in My Computer, right click on C Drive then Properties. There just go to Tools Tab and click on Defragment now.

- Do a Antivirus/AntiSpyware scan. Personally i recommend Avira Antivirus and MalawareBytes. 

Adding additional memory (RAM) to the computer will help increase the overall speed of the computer and in some cases can also increase the load times of your computer. Today, we suggest all computers be running a minimum of1GB of memory in their computer. If your computer is running less than this it may be time to upgrade.

Corrupt, incorrect, or out-of-date drivers can cause a number of different issues. Make sure your computer has the latest drivers as well as any available Microsoft Windows updates.

Although we don't often recommend registry cleaners in some rare situations running cleaners can help improve the overall performance of Windows including the Windows startup. If you've run through all of the above recommendations you may want to clean your system registry.

Just Go to task manager and check the CPU and ram usage and then to Services tab to check that which unnessaccary services are running shutdown them ,

The other reason for this problem might b virus ,you should run antivirus program to check any viruses . 

In case where the user feels the computers is runnining not at the optimum speed then the first thing the user has to go to the task manager by pressing CNTRL + ALT + DEL and then go to the performance tab which will give the statistic of the computer in terms of memory used and available, available system resources, RAM used, disk capacity etc and accordingly the user have to take the necessary steps to increase the speed of the machine to its capacity.

1.Disconnect from network.

2. Close unwanted process in task manager & stop unwanted services also through msconfig.

3. Run Ccleaner and delete temporary files, registry clean

4. Run full scan your antivirus.

5. If all these steps not working. Can restore windows(after take backup).

Try this steps, surely resolve the issue. I am doing this steps in my office. Working cool....

first thing is when hhd reach the life span of2years the effect of this is to slow response when loading program.2nd is became slower if too much bad sector in cylinder.registry error also may effect the speed of ur computer.and the last toomuch virus cookies.

try to keep some free space in your computer. if there is slow start up you can disable various start up programs that may be running.

First I check the resource monitor to see who's eating up my processing power.Then I will try to end its process tree, IF it is from a recognisable programs such as games or apps.All thing fails, I'll do system restore. Hardware problems disturbs in a different and more annoying way.

It depends upon some parameters where we check if pc is working fine and suddenly working slow it may cause of someone is syncing data from shared folder in your pc, If pc is permanently slow this means there will be loads of application installed  or lack of system drive space or there will be hardware issue like bursting of the capacitors or network card has broadcasting error or network switch/router broadcasting error but this kind of problem will occur on all of connected devices to that switch /router. Any Harddisk media weakness is also slowness cause,