At first I wanna say that your website is well designed...
Now Below Is The Review For your website
Some Positive Sides
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1) The post loading of images after scrolling down is good for site speed.
2) Your website is well seo optimized.
Improvement Tips
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1) You need to use gzip compression on your website using cpanel(search youtube). This will reduce the size of your website and reduce the loading time.
2) Enable browser caching for your static contents or contents that does not change more often.(Search Youtube)
3) you can give H2 heading tag subtitles or descriptions.
4) rename your sitemap file from "sitemap_index.xml" to "sitemap.xml" or "sitemap-index.xml" as the underscore is not seo friendly and google recommends users to use hyphen instead of underscore.