Freron MailMate

I'm experiencing an issue in which when composing a reply and signing with SMIME is turned on, mailmate hangs for several seconds (though one time for almost a minute). To recreate:
1. Have SMIME setup with signing turned on for every email
2. Ensure 'Enable message preview' is on as well
3. Hit reply on an email
4. Make sure the icon for signing is on the 'check'
5. Start typing a response.

While typing, the preview will show a green (if SMIME is setup properly) banner that indicates the signature is good. However on my system this is when the lagging start to occur and the spinning wheel of death occurs. If you continue to type the banner will typically disappear and start to lag again once you stop typing and it tries to apply the signature again.

This email sounded somewhat similar: https://lists.freron.com/mailmate/2012-November/000423.html

Let me know if I can provide more information to help debug! Thanks!