How to Increase System Speed

           Steps to Boost Up Your PC

Remove temporary files

Open CMD type below command

%temp%

temp

prefetch

Then stop unnecessary startup services

Open CMD type

Msconfig

Select diagnostic startup from the general tab

Click Hide all Microsoft services box from the services tab

Then click ok, apply, and restart the PC.

Remove all unnecessary programs from ADD/Remove programs.

Run Disk Cleanup in C: Drive

Run Registry Clean (third party software) 
Download link:
mirror1= http://download.piriform.com/ccsetup418pro.exe
mirror2: http://fs37.filehippo.com/6332/de7adc7902ab4c38b927f3fee6ac8b61/ccsetup418.exe 

Increase Virtual Memory from systems properties.

Set visual effect setting to best performance

Update windows (run windows update)

You can also, use Revo uninstaller a third-party software through it you can remove the software from the registry also.
Download link: http://9d4da85dff3fdd198886-459beec849893df302ec58f8a71b3ad1.r61.cf1.rackcdn.com/revouninstaller.zip

Sometimes your OS (XP,win7,win8) is running ok but due to application the problem, a particular application may be run slow in that case you have to check that application.

If all these things do not work then you have to Re-format your pc or Upgrade RAM.