While you can prevent individual elements from becoming available to certain user groups (using the "User Group Access Rules" in the settings for the original WP Bakery Page Builder plugin), the elements are technically still loaded in the background. In order to allow for an improved overall site performance, you can completely disable unwanted elements that are part of "Composium - WP Bakery Page Builder Extensions" here. Once disabled, the element and its associated shortcode will not be loaded anymore. Also, on default, not all elements are activated upon first plugin activation, so please check the list and the select the elements you are planning to use.
Every additional element (or feature) you activate will increase the memory load this add-on is having on your WordPress site and naturally impact overall WP Bakery Page Builder performance. Please ensure that yourserver is providing sufficient memory to handle all elements and features you are planning on using!
If you are using the "User Roles Manager" provided by WP Bakery Page Builder itself, you MUST assign the new elements to the respective user roles that are allowed to use/edit them, using the role manager inside the actual WP Bakery Page Builder plugin settings.