提高网站的绩效得分

I am using wordpress 4.5.4 with 'Jupiter' theme(version 5.1.7).

Here is link of my theme: http://demos.artbees.net/jupiter5/

My site is too slow. I have analysed site using gtmetrix.com. It is giving the score of "Add Expires headers" under yslow is 0.
I have used 'Far Future Expiry Header' plugin. Still it is not working. still the score of 'Add Expires headers' is 0. Noting improved.
Also I have used following code in .htaccess, but the result is same.

<IfModule mod_expires.c>
ExpiresActive on

# Your document html
ExpiresByType text/html "access plus 0 seconds"

# Media: images, video, audio
ExpiresByType audio/ogg "access plus 1 month"
ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/jpeg "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
ExpiresByType video/mp4 "access plus 1 month"
ExpiresByType video/ogg "access plus 1 month"
ExpiresByType video/webm "access plus 1 month"
ExpiresByType text/x-javascript "access 1 month"
ExpiresByType text/css "access plus 1 year"
ExpiresByType application/x-shockwave-flash "access 1 month"
ExpiresByType image/x-icon "access 1 year"
ExpiresDefault "access 1 month"
</IfModule>

So is there any another way to do this?

Any help/suggestion would be appreciated.

Have you tried the W3 Total Cache plug-in? It should not only take care of the Add Expires headers issue, but also improve the performance score of your site in (several) other ways:

https://wordpress.org/plugins/w3-total-cache/

(The default config should itself boost the score, but you can also tweak and tune a large number of settings/options for further performance boost.)