What is faster: hook_form_alter or hook_form_FORM_ID_alter?
The hook_form_FORM_ID_alter is faster than hook_form_alter.

Modules can implement hook_form_FORM_ID_alter() to modify a specific form, rather than implementing hook_form_alter() and checking the form ID, or using long switch statements to alter multiple forms.

Form alter hooks are called in the following order:


hook_form_alter()
hook_form_BASE_FORM_ID_alter()
hook_form_FORM_ID_alter()


I hope this helps :)