Original sentence: As you can guess however, if your Active Directory deployment has only a single domain, then the Infrastructure Master role does no work at all, and even in a multi-domain environment it is rarely used except when complex user administration tasks are performed, so the machine holding this role doesn't need to have much horsepower at all
Edited sentence: As you can guess however, if your Active Directory deployment has only a single domain, then the Infrastructure Master role does no work at all, and even in a multi-domain environment it is rarely used except when complex user administration tasks are performed.Because of this, the hardware requirements for machines holding this role are relatively small