Slow page load with 1000s of markers

Hi,
I’ve got many 1000s of markers for posts to display on the map.
Up to 500 the page load is ok, just about.
1000 it won’t load.

I am using a function in a page template as this works better than the shortcode, which doesn’t load after a few hundred.

Here’s the code:

if ( function_exists( 'pronamic_google_maps_mashup' ) ) {
	pronamic_google_maps_mashup(
		array(
			'post_type'      => 'post',
			'posts_per_page' => 500,
		),
		array(
			'width'  => 800,
			'height' => 500,
			'map_type_id'    => 'satellite',
			'overlapping_marker_spiderfier_options' => array(
				'markersWontMove'        => false,
				'markersWontHide'        => false,
				'keepSpiderfied'         => false,
				'nearbyDistance'         => 20,
				'circleSpiralSwitchover' => 9,
				'legWeight'              => 1.5,
			),
		)
	);
}

Can I add pagination to load batches of markers and allow the user to select the page?

Can I also add category filters for the user to select so the map only loads those post in a selected category?

Thanks

https://www.ads-software.com/plugins/pronamic-google-maps/