I wrote a tutorial in the past about optimizing a Dolphin database using phpMyadmin. This latest tutorial is based on Dolphin 7.1.x screenshots, and includes a step by step walk through video that is easy to follow along with.
It is very easy to perform, and can be completed in a matter of seconds.
Login to your hosts control panel.
Click and open phpMyadmin.
Find your Dolphin database on the left side of the page, and click on it.
Scroll to the bottom of the page.
Find and click on the "Check tables having overhead" link to select all the ones with overhead.
Then, in the drop down choose "Optimize table".
You should see a success message after doing so.
You do not need to worry about a few bytes or kilobytes of overhead in your Dolphin database. This is not something that you would need to do on a daily basis. Once or twice in a given month is usually more than sufficient for most sites.
The process is the same for previous Dolphin versions as well.
This is not Dolphin specific. If you use other CMS database driven scripts you can apply the same steps above to optimize them as well.
Be sure to watch the video tutorial near the top of this page for a complete step by step walk through on how to do this. It's around 5 minutes long.