Mail terribly slow after upgrading to Yosemite

This was very helpful.

For the technically uninitiated, Mail.app is storing some data apart from your messages to help it organize things in a database. Over time, that database can become... filthy. What the command does is rebuilds that database from scratch -- copying all of the valuable data -- so that inefficiency that crept in over time is cleaned up.

The second reply from Linc Davis is just another way to do this, but one that is more destructive. The first answer is actually the safer way.

Also, apparently switching away from the "Classic" layout has helped some people. Mail.app is also pretty slow with GMail right now.

Hi Linc

This helped me immensely. Mail is back up and running quickly, however, it has also positively impacted the overall performance of Yosemite, Messages and the boot time of other non-Apple applications. I have a hypothesis that the duplication of mail files had essentially added additional CPU load that meant less CPU cycles and RAM space available for other apps. So, thank you.

Cheers

Brother M

Thank You.

This seems to have helped.

Do we need to ran this command again after sometime? how long do we often ran this purging? 6 months? 1 year? or ran it once and will fix your mail woes?

Is the command permanent as well? - meaning do I need to ran this after rebooting our machine or only ran once?

What does this command actually do?

Can someone point me to the path of the database location?