this topic was closed: https://theme.co/apex/forum/t/cornerstone-and-pro-performance/13542
my provider took over 10 days to reply…
here is the latest machine translation of his reply:
I have clarified in several places what the possibilities are. Unfortunately, nothing can be done here except to optimize Cornerstone internally. It is because of this only js file which takes longer until it is fetched. The Wordpress information is not useful because all options except Keep-Alive are already optimal.
and more information from another topic here in the forums:
Ajax requests depend on Keep-Alive connection, especially for Wordpress that has built-in heartbeat and admin-ajax. So it’s not just about Cornerstone, it’s about all scripts that will utilize Wordpress ajax.
What they are doing is optimizing it and trying to minimize the processing and resources being used. If it’s their rule then I think there’s nothing we can do about it but move to the different host. Plus, they mentioned that you’re on a shared hosting, and it’s understandable that they should limit your site’s capability since multiple sites are running on same allocated resources. Shared hosting is usually slow due to limitations, you can’t even increase the memory limit.
Please check this https://www.keycdn.com/blog/admin-ajax-php-slow/
thanks for your help! kai