CPU overusage

I have upgraded from Mailpoet 2 to Mailpoet 3 this week, initially for one day I ran it through my site but on receipt of my key, I ran it through you as recommended. Since then my Webhosting CPU Time Usage has kept exceeding the allowance causing my website to be taken down. Siteground said it was because of Mailpoet.

At the moment I only have 10 subscribers (most people follow using social media) so I am sending 10 email 3 times a week.

They suggested I change plugins or remove the Chron?

I am a capable computer user but I am not a programmer so I’m not sure what they mean by the Chron.

Do you have any suggestions how I can continue to use Mailpoet 3?