Fortunately, WordPress comes inbuilt with this support. It integrates with Google Gears that enables you to cache the files for offline use. And enabling it is so easy.
At the top right of the dashboard you will see a link called Turbo.
Hitting this will redirect you to the Tools page. You can also reach this link via the Tools menu in the left sidebar.
The first thing you will see is the section title Turbo: Gears Status as shown in the screenshot below. Simply hit the Enable Gears button.
You will be either prompted to install gears or you will be asked to grant permission to your blog to use Gears.
This will cause the files of the admin area to be cached for local use by Gears. Once this process is complete, you’ll notice that your admin area loads a lot quicker than it did before.