I just ran Page Speed Insights on my website that I built with bold grid, and it is extremely simple (2 pages with only 4-5 uploaded images), and I got not-very-good scores for mobile & desktop.
Most of the issues appear to be related to your theme. Do you have some recommended plugins to improve page load speed?
Thank you for your question regarding optimizing your site. As is the same with any site using built on a WordPress back end, you will want to be mindful of any plugins or background services utilizing resources. Then you will want to make use of caching with a popular plugin like Comet Cache, W3 Total Cache, or whichever you prefer.