Hello Atul,
If your MacBook Pro is running slow, take a look at the resource below for some possible reasons why:
OS X El Capitan: If your Mac runs slowly
If you find your Mac is running slowly, there are a number of potential causes that you can check.
An app you’re using may require more memory than your computer has easily available. To see how much memory your computer has, choose Apple menu > About This Mac, then check the amount of memory listed in the Overview panel. See the help that came with the app to find out its system requirements.
To find out how to increase your computer’s memory, choose Apple menu > About This Mac, click Memory, then click Memory Upgrade Instructions in the lower-right corner. (Not available on all computers.)
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To see what processor your computer has, choose Apple menu > About This Mac, then click Overview.
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To see what graphics card your computer has, choose Apple menu > About This Mac, then click Displays. The name of the graphics card in your computer is displayed in the middle of the window.
Your computer’s startup disk may not have enough free disk space. To make disk space available, move files to another disk, then delete files you no longer need on the startup disk.
Quit any apps you’re not using.
If you have problems with your disk, use Disk Utility to verify and try and fix any issues.
Use Activity Monitor to see if a particular app or activity is making a large demand on your Mac.
Last Modified: Apr 13, 2016
This resource provides more detailed information on how to locate large files on your MacBook Pro and move them to another disk to free up space on your internal hard drive. Make sure you have a backup of your computer before making changes to it.
Use Time Machine to back up or restore your Mac
OS X El Capitan: Increase disk space
Have a great day!