Slow loading of markers

Hi, I have about 25 locations in my map, also filtering options as well. My issue is with the markers loading on the map. They are very slow indeed. The whole page takes 3 seconds to load, which loads the map as well. The backend process for building markers and lists takes about 5-8 sec. Created a custom template link for map page which I removed all unnecessary js and css files from other plugins. Still no avail. Created some shortcodes along with existing ones which fetches extra info from posts. So how do I load markers faster. Can we build a json array, so it does not need to build on page load or something. Thanks..

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