Can the Optimizer also crawl subdomains or directories?

Yes, the SISTRIX optimizer is able to not only crawl entire domains but also specific subdomains (hostnames) and directories. When starting a project, you can specify whether the domain, a subdomain or a directory should be crawled and analyzed.

The setting can be changed in the project settings (Settings -> Project). Please keep in mind that, if you change the project from a domain-wide crawl to a specific host or directory, the previously collected data will not be suitable for comparison with data from the new crawl.