Thank you for reaching us in the Community. I'm sorry to hear the site is freezing for you. I know how important it is to get your email campaigns out when you want to. I want to suggest a few troubleshooting steps that might alleviate the situation.
Are you receiving any error messages when it freezes? If this issue persists please email us at social_support(at)constantcontact(dot)com with your username, the troubleshooting steps you have tried, and a reference to this post. I will make sure we investigate!