Is it Philosophy by any chance? My friends are doing their timed conditions Philosophy essays at the moment. You just need to remember the key points, there's no point trying to learn all of it off by heart, depending on the length. It can be done, it depends if you're good at learning things off by heart in general. For my Italian oral I've had to memorise 2 A4 pages of arguments and I did most of it the space of a few days, I listened to some music, learned a sentence or two, listened to some more music, then learned some more, and so on! I just gave myself really short, regular breaks and kept reciting it aloud to myself.