TTFB is too slow in back-end [closed]

A simple solution (although not followed by good practices) would be to use a CACHE plugin. This will use an image of your HTML and you will not have to execute your process every time. If you want to improve the performance of the PHP file, you should find the root of the problem, that … Read more

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