Not sure if anyone has run into this issue. I use evolution 3.12 on Ubuntu 14.10. After the initial install every thing worked great but over time Evolution started slowing down and responding very slow on deletes and move of the emails to folders. on opening new emails it consistently showed a blank screen which I had to close the email and open it back up. On sending emails it would leave a draft email in the draft folder even I confirmed that the email was sent.
After a lot of research I found the solution and wanted to share just in case someone else is having the same problems.
Shut down evolution
Go to home folder and do a "ctrl H" to show the hidden folders. Navigate to /home/.cache/evolution. (make a tar file of all the directories in that folder just in case) Delete all the files and directories under evolution.
restart evolution and let it sync all the folders That fixes the problem.
Keep in mind that it might delete your local address book so make sure you have a back up so you can import it back in.