Thanks for your answer. I can add this comment from moodle administrator
"The plugin cannot be used to run an exam.
There is an architectural problem directly in the plugin: it serves static files (images, style sheets, JavaScript, etc.) through a dynamic file (PHP).
We allow 128 concurrent processes (workers). Normally, a process lasts only a few milliseconds, so this does not reach saturation.
With this plugin, because it serves large files, it takes much longer and the workers become saturated very quickly.
For example, there is a JavaScript file of about 500 KB.
Static resources should generally be served directly through HTML (via Apache), not through PHP. This is a legacy of older Moodle practices.
Unfortunately, it is not possible to increase the number of workers without causing side effects elsewhere.
That is why, for example, we host videos externally.
We have therefore reported the issue to the module developers. When a corrective patch is released, we will deploy it."
You are right "Moodle admin staff tell me it's not possible"
"The plugin cannot be used to run an exam.
There is an architectural problem directly in the plugin: it serves static files (images, style sheets, JavaScript, etc.) through a dynamic file (PHP).
We allow 128 concurrent processes (workers). Normally, a process lasts only a few milliseconds, so this does not reach saturation.
With this plugin, because it serves large files, it takes much longer and the workers become saturated very quickly.
For example, there is a JavaScript file of about 500 KB.
Static resources should generally be served directly through HTML (via Apache), not through PHP. This is a legacy of older Moodle practices.
Unfortunately, it is not possible to increase the number of workers without causing side effects elsewhere.
That is why, for example, we host videos externally.
We have therefore reported the issue to the module developers. When a corrective patch is released, we will deploy it."
You are right "Moodle admin staff tell me it's not possible"