Dynamic Menu from multiple JSON files – Jquery

MAYUR, I ended up with the following. It works perfectly however it is a little slow. If you have any tips on improving the speed, let me know:

$(document).ready(function() {
    
    // 1.) create an attributes (trait) array
    // 2.) loop through the items, check if the trait is already in the array, if not then add it
    // 3.) loop over attributes array and create the menu items off that.
    
    var getItemData = async function(id) {
        
        const itemURI = "https://ikzttp.mypinata.cloud/ipfs/QmQFkLSQysj94s5GvTHPyzTxrawwtjgiiYS2TBLgrvw8CW/"
        return await $.getJSON(itemURI+id);
    }
    
    var loopFunction = async function(dataIsLoading) {
                    
        var items = {};
        var promises = [];
        
        for (let i = 0; i < 1000; i++) {
                
            // Get data and add to promises array:
            promises.push(getItemData(i));
        }
        
        // Wait on all promises:
        return await Promise.all(promises).then(function(promise) {
            
            // Loop over each returned promise:
            $.each(promise, function(index, data) {
                
                // Loop over attribute data:
                $.each(data.attributes, function(index, entry) {
                    
                    let menuParent = entry.trait_type;
                    let menuChild = entry.value;
                    let menuParentItem = {};
                    
                    // Check for menuParent:
                    if (items.hasOwnProperty(menuParent)) {
                        
                        // Get menuParent:
                        menuParentItem = items[menuParent];
                    }
                    
                    // Check for menuChild:
                    if (!menuParentItem.hasOwnProperty(menuChild)) {
                        
                        // Add menuChild:
                        menuParentItem[menuChild] = menuChild;
                    }
                    
                    // Update items object:
                    items[menuParent] = menuParentItem;
                });
            });
            
            // Return items.
            return items;
        });
    };
    
    $.when(loopFunction()).done(function(items) {
        
        // Loop over all items creating the markup.
        var menuItems = '';
        
        $.each(items, function(menuParent, menuChildren) {
            
            menuItems += '<li class="menuParent"><b>' + menuParent + '</b>: <ul>';
            
            // Loop over menuChildren.
            $.each(menuChildren, function(menuChild, menuChildValue) {
                
                menuItems += '<li class="menuChild">' + menuChild + '</li>';
            });
            
            menuItems += '</ul></li>';
        });
        
        // Render menu items.
        $('#myList').append(menuItems);
    });
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<ul id ="myList">
 
</ul>