Dion

UsageDD allows administrators to monitor the resource usage of their WordPress installation. It will add a small box at the bottom center of each page, only visible to administrators, that displays the number of MySQL queries, the amount of memory used by the page’s code, and if you are using a compatible webserver (most are compatible), the “time to first byte” (TTFB) and the time required to generate the full page. TTFB is used by Google for page-ranking purposes, and it will be the first of the two displayed.
You can use the display to determine if your site has too many plugins loaded, if your theme is too “heavy”, or if something is wrong on your server. The plugin itself uses virtually no resources and should be compatible with every theme and plugin that outputs HTML.
Support is available in our <a href="https://forum.dion-designs.com/f35/usagedd-support/" rel="nofollow ugc">dedicated support area</a>. Support questions posted on wordpress.org may go unanswered for an extended period of time.

UsageDD

UsageDD allows administrators to monitor the resource usage of their WordPress installation.

Vasileios Kerasiotis

The archives WordPress plugin. This plugin creates real posts archives and greatly reduces the DB load since old posts are called only when needed. This plugin is great for sites with thousands of posts!!!
You can read more about it here: http://jeez.eu/2011/03/14/qoolarchives-an-archives-wordpress-plugin.html and you can also visit http://www.qoolsoft.gr for more info

QoolArchives

The archives Wordpress plugin. This plugin creates real posts archives and greatly reduces the DB load since old posts are called only when needed.

UsageDD vs QoolArchives