Now this may seem rather obvious, but many WordPress users enable an option that slows down postings even when the option actually warns you that this slows down postings. If WordPress just seems slow to you when you are adding content, make sure that under Options – Discussion Options – Attempt to notify any Weblogs linked to from the article is cleared and not checked. This will stop WordPress from pinging multiple websites and slowing down the posting process.

For speeding up WordPress for viewing, you need to install WP-Cache 2, which is an excellent plugin and in my opinion one of the top essential WordPress plugins.

Once your WordPress databases grow, you should definitely take the time to optimize your MySQL databses. The process is quite simple and the benefit is immediate.