This is the queen of all sandboxes as it reproduces the production environment. Indeed, this sandbox type can be used for performance testing. That being said, it is a full copy of production regarding both metadata and data, and it is aligned with production limits for file and storage quotas. The refresh time is 29 days. However, you can always apply a sandbox template to select the objects you want to be copied.

Why don't you want all the data? There may be certain objects that are useless for your testing.

Copying GBs of data can be time-consuming and you should expect your sandbox creation/refresh time to take several days. The less you need to copy, the faster the copying process is.

When creating/refreshing a Full sandbox, Salesforce asks you what you want to do with field tracking information. You can decide not to include it (faster copy) or you can go up to 180 days back in time (chatter history can be very large).

Because of their nature, Full sandboxes are used for testing external integrations (as external systems expect real production data) or staging for the final validation of your team's work or for production debugging.