Hey, here i m going to introduce some plugins which is a must for your site. I hope this will help someone who search for better wordpress performance. I always use the best wordpress plugins for my projects, because they will have best support and documentations so that it will help us to use with ease.
Akismet (For Spam Filtering)
Hope you all heard about spam issue in wordpress, Akismet is the best solution to the spam issue. Akismet helps to reduce almost all spams.
Google Xml Sitemaps
This plugin will generate a special XML sitemap which will help search engines like Google, Bing, Yahoo and Ask.com to better index your blog.
All in one SEO Pack(SEO)
All in One SEO Pack Optimizes your WordPress blog for SEO (Search Engine Optimization).
or WordPress SEO Plugin by Yost
As per Yost, the most complete SEO plugin for WordPress available today offers you everything you need to optimize your site.
Contact Form 7
This is the best solution for adding contact form in your website. Flexible, and simple.
Nextgen Gallery (For gallery)
For wordpress, i suggest nextgen gallery because it is friendly, easy to use, more functionality including image re sizing, image comments etc.