Tools to optimize the performance for SharePoint 2010 Server

Large List throttling is good for limiting the load time on lists with large numbers of items
HTTP Request throttling can keep the server from losing data during high utilization
Developer dashboard can be used to monitor performance on page loads

By default the Developer Dashboard is turned off. When the Dashboard is on, every page will render the dashboard, all the time. In on-demand mode, the dashboard can be accessed as needed by web administrators.

When the Developer Dashboard is turned on, it will only be visible to users with Full Control.
This means that for example on a My Site when the Developer Dashboard is turned on, the user who has full control on his/her my site will be able to see the dashboard.

What information is visible on the dashboard:
- times to render various components on the page
- pages checkout level
- database query information
- web part processing time
- any critical events or alerts

Good for diagnosing problem web parts on a page or long list load time

How to enable the Developer Dashboard?
stsadm -o setproperty -pn developer-dashboard -pv OnDemand (Off or On)

Its a Farm wide setting!

When you're able to see the dashboard you can also see a correlation ID which you can use to trace the ULS logs.