Extreme slow Views rendering time
Views can create real bottleneck for scaling and often cause great head ache by becoming resource hungry if not optimized well. Especially the use of Left Joins instead of Inner Joins, the default pagination in views and features like Distinct are major causes for the same.

The below code is a quick sample implementation which probably could fix the join issue in a view.

/**
* Implements hook_views_query_alter().
*
* This disables distinct and turns LEFT joins into INNER joins. This increases
* performance.
*/
function my_module_views_query_alter(&amp;$view, &amp;$query) {
if ($view-&gt;name == "my_view") {
$query-&gt;table_queue['content_type_article']['join']-&gt;type = 'INNER';
$query-&gt;distinct = 0;
}
}


Also, check if you can enable views cache. You can set the interval to something based on your update frequency or try to clear views_cache when something is updated on the site.

Use of views_litepager instead of the default page can also help, if you are using pagination in views.

There are several things you can do. You could read this detailed post on the topic for a more detailed understanding.