Adding few more points:
1) Disable comments, RSS,Pingback if not necessary.
2) Optimize your .htaccess file for speed up the cache. headers, compression, server side tweaks.
3) Tweak the php.ini file with increasing memory, post size, upload size
4) use CDN such as MaxCDN, Cloudflare
5) Use the right plugins for optimize the performance ( WP Super cache, WTC,etc)
Checkout my full tips from here : Wordpress Performance Optimization Tips
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