Gatsby is a powerful tool for building complex websites quickly, but it can be slowed down by certain factors. To optimize Gatsby builds, take advantage of the cache, enable incremental builds, store images in your repository no larger than you need them, only query for data you actually need, and run through the advanced Gatsby build optimization checklist. Additionally, consider disabling file fingerprinting to speed up deploys, ensuring asynchronous requests run in parallel, making Gatsby image build performance faster with parallel processing, skipping image processing altogether, and exploring specialized asset hosting options like Cloudinary. By implementing these optimizations, you can significantly improve your Gatsby build times.