Problem:
Output custom post types by using views queries on pages.
The pages loads very long time. The more I add view queries the longer it takes. If I remove all view queries from the page at all, it loads quickly. What am I doing wrong?
Solution:
I checked the problem page URL you mentioned above, but keep on getting the PHP error:
Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0
For the performance problem:
there are about 20 shortcodes [wpv-view] in that page, so you are display 300 + Tools posts with 20 view in same page, it will consume more server capability.
Here are my suggestion:
1) Your website MemoryLimit setting is 256M, it is too small to run 33 plugins, I suggest you Increase PHP memory limitation
https://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP
2) In case it is a compatibility problem, please deactivate other plugins and switch to wordpress default theme, and test again
3) Enable PHP debug mode, copy and paste the debug logs here
PHP Debugging
In case you think that Types or Views are doing something wrong (what we call a bug), you should enable PHP error logging. Again, edit your wp-config.php file and add the following:
ini_set('log_errors',TRUE);
ini_set('error_reporting', E_ALL);
ini_set('error_log', dirname(__FILE__) . '/error_log.txt');
This will produce a file called ‘error_log.txt’ in your WordPress root directory. Make sure that the web server can create and write this file. If it cannot, use an FTP program to create the file and make it writable to Apache (normally, user www-data).
https://toolset.com/documentation/user-guides/debugging-types-and-views/
Relevant Documentation:
https://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP
