Venkat Raj

@dmvisuals As per the debug log, it says an object is given instead of array to array_key_exists functions. The given $headers is the return value of get_stylesheet_headers function.

In 3.2.13 it is directly returned . As you can see here.
https://plugins.trac.wordpress.org/browser/wp-optimize/tags/3.2.13/wp-optimize.php#L1648

However, in 3.2.14 the return value was made sure an array which you can see here.
https://plugins.trac.wordpress.org/browser/wp-optimize/tags/3.2.14/wp-optimize.php#L1648

So, I’m not sure how the issue persist. May be the update is incomplete?

@edviser Thanks for the details. I’ll try to reproduce the issue and update you.

@andreas-2013 Please add following line in your wp-config.php file
define('WP_OPTIMIZE_SET_TIME_LIMIT', 300);

This will result in 5 minute preload chunks

@vladimirvuch I have tried to reproduce the issue with no luck.

I have tested with setting serve cached pages to logged in users both turned ON/OFF.

https://prnt.sc/8KzWPfJV9jVw

I used Elementor Pro and Hello Elementor theme

@andreas-2013 When you reduce the time limit, the usage spike will be for short periods rather than long. One possible explanation for high memory usage is that if your site uses lots of different set of scripts/styles in each pages, then minify assets will be created for those sets separately.

Could you please deactivate/activate the WP-Optimize and see if that fixes issue?

That said, it seems system (disk I/O, network communication, etc) too take lot of resource apart from WP-Optimize’s PHP process?

@andreas-2013 All preload is doing that it visit’s your site programmatically. So, it will take the same amount of resources if you visit the pages manually.

The preload doesn’t run as a single task. Once the PHP script reaches the time limit (max_execution_time), the remaining URLs are scheduled to preload later. We do see the possibility and increase the time limit to 30 minutes. What you have done is that increase the interval between batched preload tasks.

If you don’t want to run a single preload task for 30 minutes, then you can reduce it by defining a constant WP_OPTIMIZE_SET_TIME_LIMIT to your desired seconds.

@vladimirvuch What theme and plugin you are using for that functionality?

@fkoomek You could use Schedule preloader option and set schedule type as same as cache lifespan

This runs preload whenever the cache is purged.