There are a handful of games that a 4C/4T CPU will limit performance on a GTX 1060 and up, and AC Origins is one of them. Recommended requirement is an i7-3770 for both AC Origins and AC Odyssey. The only thing other than upgrading CPU and maybe RAM is doing what @boju said along with getting rid of any background tasks using the CPU.
I've heard the pagefile on the hdd being used when the RAM isn't enough, but I'm not sure that's an issue with most games.