Make a php array load faster

Question

I successfully edited the checkout page of the WooCommerce city field in order to be a dropdown field with a lot of cities in it around 13k values the problem is that on mobile and some low-end devices this field isn't performing well how I can make this array load faster is a DB call worth it in this situation, is there any way stop the dropdown and make the field only searchable is it worth splitting the array or loading from a text file?

The code I made

<?php

// Add custom checkout select fields
add_filter('woocommerce_checkout_fields', 'add_custom_checkout_select_fields');
function add_custom_checkout_select_fields($fields)
{
    $arr = array(); // very big array arround 13k values
    

    // Define HERE in the array, your desired cities
    $cities = $arr;

    // Format in the right way the options array of cities
    $options = array(
        '' => __('Choose City', 'woocommerce') . '&hellip;'
    );
    foreach ($cities as $city)
    {
        $options[$city] = $city;
    }

    // Adding 2 custom select fields
    $fields['billing']['billing_city2'] = $fields['shipping']['shipping_city2'] = array(
        'type' => 'select',
        'required' => true,
        'options' => $options,
        'autocomplete' => 'address-level2',
        'input_class' => array(
            'wc-enhanced-select',
        )
    );

    // Copying data from WooCommerce city fields
    $fields['billing']['billing_city2']['class'] = array_merge($fields['billing']['billing_city']['class'], array(
        'hidden'
    ));
    $fields['shipping']['shipping_city2']['class'] = array_merge($fields['shipping']['shipping_city']['class'], array(
        'hidden'
    ));
    $fields['billing']['billing_city2']['label'] = $fields['billing']['billing_city']['label'];
    $fields['shipping']['shipping_city2']['label'] = $fields['shipping']['shipping_city']['label'];
    $fields['billing']['billing_city2']['priority'] = $fields['billing']['billing_city']['priority'] + 5;
    $fields['shipping']['shipping_city2']['priority'] = $fields['shipping']['shipping_city']['priority'] + 5;

    wc_enqueue_js("
    jQuery( ':input.wc-enhanced-select' ).filter( ':not(.enhanced)' ).each( function() {
        var select2_args = { minimumResultsForSearch: 1 };
        jQuery( this ).select2( select2_args ).addClass( 'enhanced' );
    });");

    return $fields;
}