The normal generation of thumbnails requires that some components exist on the web server and that a parameter in config.inc.php be correctly configured.
phpMyAdmin uses internally some functions to create the thumbnails. These functions need the GD2 library to be present on our PHP server.
phpMyAdmin can detect the presence of the correct GD2 library, but this detection takes some time, and takes place not once per session, but on almost every action taken in phpMyAdmin.
Setting the $cfg['GD2Available'] parameter in config.inc.php to its default value,'auto' indicates that a detection of the library's presence and version is needed.
If we know that the GD2 library is available, setting $cfg['GD2Available'] to yes will make execution quicker. If the GD2 library is not available, you are recommended to set this parameter to no.
To find out which GD2 library we have on the server, we can go to phpMyAdmin's Home page, and click Show PHP information...