FullCalendar with JSON feed loading slowly - wordpress

Question

I'm using FullCalendar to load events from custom post types on WP, through a JSON feed. It's working, but it's taking some time to load. Please check here: http://cea3.iscte.pt/en/agenda-3/ (june or august). Do any of you have a clue what can be causing it?
This is the full code for the JSON feed:
<?php
// - standalone json feed -
header('Content-Type:application/json');
// - grab wp load, wherever it's hiding -
if(file_exists('../../../../wp-load.php')) :
include '../../../../wp-load.php';
else:
include '../../../../../wp-load.php';
endif;
global $wpdb;
// - grab date barrier -
$oneyear = strtotime('-1 year') + ( get_option( 'gmt_offset' ) * 3600 );
// - query -
global $wpdb;
$querystr = "
SELECT *
FROM $wpdb->posts wposts, $wpdb->postmeta metastart, $wpdb->postmeta metaend
WHERE (wposts.ID = metastart.post_id AND wposts.ID = metaend.post_id)
AND (metaend.meta_key = 'tf_events_enddate' AND metaend.meta_value > $oneyear )
AND metastart.meta_key = 'tf_events_enddate'
AND wposts.post_type = 'tf_events'
AND wposts.post_status = 'publish'
ORDER BY metastart.meta_value ASC LIMIT 500
";
$events = $wpdb->get_results($querystr, OBJECT);
$jsonevents = array();
// - loop -
if ($events):
global $post;
foreach ($events as $post):
setup_postdata($post);
// - custom variables -
$custom = get_post_custom(get_the_ID());
$sd = $custom["tf_events_startdate"][0];
$ed = $custom["tf_events_enddate"][0];
// - grab gmt for start -
$gmts = date('Y-m-d H:i:s', $sd);
$gmts = get_gmt_from_date($gmts); // this function requires Y-m-d H:i:s
$gmts = strtotime($gmts);
// - grab gmt for end -
$gmte = date('Y-m-d H:i:s', $ed);
$gmte = get_gmt_from_date($gmte); // this function requires Y-m-d H:i:s
$gmte = strtotime($gmte);
// - set to ISO 8601 date format -
$stime = date('c', $gmts);
$etime = date('c', $gmte);
$thetitle = $post->post_title;
$short_title = substr($thetitle,0,50);
$eventpostid = $post->ID;
$eventslug = wp_get_post_terms( $eventpostid, 'tf_eventcategory' );
$eventvenueslug = $eventslug[0]->slug;
$tf_events_link = get_post_meta($post->ID, 'tf_events_link', true);
$tf_events_permalink = get_permalink($post->ID);
if ($tf_events_link) { $url_event = $tf_events_link ; }
else { $url_event = $tf_events_permalink; };
// - json items -
$jsonevents[]= array(
'title' => $short_title . '...',
'allDay' => false, // <- true by default with FullCalendar
'start' => $stime,
'end' => $etime,
'url' => $url_event,
'className' => $eventvenueslug
);
endforeach;
else :
endif;
// - fire away -
echo json_encode($jsonevents);
?>
Thank you.

Answer 1

It does seem like it takes a few seconds to load.
I use this calendar and it takes about 2-6 seconds to load- The longest was 6 seconds but i had about 3 sources and ~40 events.
Now I am not sure if that for you is a long time because you did not specify how long it actaully takes.
It looks like the call is on the same server so the only problem can be the SQL that takes long to reply. Is it dedicated or shared server?
Your PHP looks fine and should execute quickly. I have similar logic using .NET and SQL Server.
This is the time it takes to load your calendar from my side of the world.
The only other way to speed it up is to use Caching
http://arshaw.com/fullcalendar/docs/event_data/events_json_feed/#options
and manage it to reload the source somehow with a clever check of the date? or something.
I am sure the times would be reduced to ms once the feed has been loaded before.
You would have to do something clever like load the current month quickly - and in the background load 1 year or 2 years and cache it. Then when you change months it will be instant because its in memory.