Hi @fabuky,
Thank you so much for sharing.
One thing to speed up the page load is to use pagination in your page/blog posts.
Here are other recommendations.
1- Check your image sizes: The larger your images, the more dramatic the difference. We would suggest optimizing your images for the web by resizing them to 1920px the longest side before uploading it to your site or through the Manage Gallery. Here is how you can do that using NextGen Gallery: https://www.imagely.com/docs/resizing-images/
2- Check the first load vs subsequent load. Could you confirm whether or not after reloading your page with your gallery, if opening it up again in a different browser helps?
3- Remove any plugins you don’t need. Consider deactivating Jetpack, which together with NG for some reason seems to slow performance. A good plugin I would suggest to install to help you identify the larger plugins that use a lot of server resources: P3 Plugin Profiler (NextGEN will be one of them, because it is a large plugin, but it will help you identify others that you might consider deactivating and removing if you aren’t using them).
4- Optimize Your Database & Remove ‘Bloat’. Install and use WP-Optimize to help optimize your database tables and remove ‘bloat’ from your site (i.e. page & post revisions, spam comments).
5- Install a caching plugin. Some highly rated ones are: W3 Total Cache or WP Super Cache.
We currently don’t have lazy loading on our regular galleries, but please, feel free to share that as a new feature request using this form https://www.imagely.com/feature-voting/
Note: We always recommend performing a full website backup before any significant change on your website.
