aMember (site.js) UX for menu with many items

site.js

jQuery(function(){
    var tolerance = 80;
    var initialStep = 30;
    var speed = 0.35;
    var step = initialStep;
    var w;

    jQuery('.am-tabs-wrapper').css({
        overflow: 'hidden'
    });
    jQuery('.am-tabs-wrapper > ul').css({
        transition: 'margin ' + speed + 's linear'
    });

    jQuery(window).resize(function(){
        w = 0;
        jQuery('.am-tabs-wrapper > ul > li').each(function(i, obj){
            w += jQuery(obj).outerWidth();
        });
        jQuery('.am-tabs-wrapper > ul').css({
            width: Math.max(w, jQuery('.am-tabs-wrapper').width() - 2) + 'px'
        });

    }).resize();

    var interval1_id = false, interval2_id = false;
    jQuery('.am-tabs-wrapper').mousemove(function(e) {

        var context = jQuery('.am-tabs-wrapper');
        var left = jQuery('.am-tabs-wrapper').offset().left;
        var right = left + jQuery('.am-tabs-wrapper').width();
        if (!interval1_id && e.clientX > (right - tolerance)) {
            interval1_id = setInterval(function(){
                jQuery('.am-tabs', context).css({
                    marginLeft: Math.max(
                            -1 * (w - right + left + 1),
                            parseInt(jQuery('.am-tabs', context).css('marginLeft')) - step
                        ) + 'px'
                });
                step += 10;
            }, speed * 1000);
        } else if (!interval2_id && e.clientX < (left + tolerance)) {
            interval2_id = setInterval(function(){
                jQuery('.am-tabs', context).css({
                    marginLeft: Math.min(
                            0,
                            parseInt(jQuery('.am-tabs', context).css('marginLeft')) + step
                        ) + 'px'
                });
                step += 10;
            }, speed * 1000);
        } else if (e.clientX >= (left + tolerance) && e.clientX <= (right - tolerance)) {

            clearInterval(interval1_id);
            clearInterval(interval2_id);
            interval1_id = interval2_id = false;
            step = initialStep;
        }
    });
    jQuery('.am-tabs-wrapper').mouseleave(function(e) {
        clearInterval(interval1_id);
        clearInterval(interval2_id);
        interval1_id = interval2_id = false;
        step = initialStep;
    });
});