Regarding to the performances, should I check if a post has a thumbnail before or after checking if is the front page (or single page, etc.)?

Neither, they are just as fast as each other, both are using information that has already been fetched in advance. This is micro-optimising. Functions such as is_front_page or is_singular etc etc are just looking up variables already set in the main query object. Likewise functions such as has_post_thumbnail etc are looking up data that has … Read more

JS/CSS duplicate load and 404 Error [closed]

Sorry to hear this. That is a lot of plugins! Since you have no worries installing/using so many, I have to ask: have to tried using a plugin to minimize and impact performance of Javascript and CSS? Might be worth trying something like this just to see how it impacts overall performance: https://wordpress.org/plugins/autoptimize/ Also, have … Read more

To what degree can use of caching-plugins and a CDN boost WordPress performance? [closed]

If your content is rarely updated and that you have configured a caching solution to have what is commonly called a ‘supercache’. This means that ounce a page is cached, next call to that page will return a static content, without requiring a call to a php interpreter. Even on a cheap hosting, you can … Read more

Is fech_feed() use lots of server resourses?

Yes it’s true your code can consume more resources then normal.Because you are working with feed and fetch_feed() consume more. It creates SimplePie object based on RSS or Atom feed from URL. You can do one thing just limiting your post as below: <h2><?php _e( ‘Recent news from Some-Other Blog:’, ‘wpdocs_textdomain’ ); ?></h2> <?php // … Read more