If you have a site with hundreds or thousands of posts and pages, there are some tips to reduce the generator build time based on the content your site needs.
To control those options, start WordPress and navigate to the Shifter settings panel.
In the Shifter Settings panel you can choose what content you would like to skip. For example, skipping media pages can reduce build times as much as 70% in most cases.
Media pages are rarely used and for each attachment you upload to WordPress, the CMS will create a new page for that upload. So, if you have thousands of media files you’ll be creating thousands of pages you don’t need.
You can take this further too by opting out of list pages such as day, or monthly archives.