Hello,
As for the maintenance mode:
1. Create a page for maintenance mode and choose the maintenance template in it.
2. Navigate to the Theme Settings > Maintenance > enable maintenance mode. If you have done all, but the maintenance does not work, deactivate all the plugins not related to the theme, and switch to the parent them if you are running the child one and provide your site admin access to the private area.
As for the side speed, our theme is already optimized and don’t have too many resources to make your website slow. Most likely, your website performance suffers from the content you have added to your website. It may happen in case of too many plugins, large not optimized images or other resources. So we suggest you to remove unnecessary plugins, install some kind of JS & CSS optimizing plugins like Better WordPress Minify and a caching plugin like WP Super Cache. Also, you can use GTmetrix tool to see what makes your website slow and optimize these parts of your website.
Best Regards
.
