Very Laggy on Mac M2, it average 13 Fps
You aren't the first to report issues with the Mac version being laggy. I've never experienced issues outside of running OBS alongside the game but I just downloaded the demo to my 2016 laptop to be thorough and it ran pretty smooth so I can't really understand where the issues are coming from. I've never been able to replicate this for myself so I'm uncertain what the issue could be unfortunately.
There's currently no official walkthroughs since content is still subject to change. But I can give you some direction in case you didn't finish yet. The main ingredients are just drops from the Slime and Shroom enemy. The specific flower you need though is located past the broken bridge. So if you haven't cleared the slime boss you just need to progress the main story. If you have then the flower is located to the right of Cheshire's shop. You might want to save as there's an optional lewd scene that can occur depending on how you pick the flower.
But after you make the medicine the quest will stall out and you won't be able to progress as the remaining parts of it take place in later chapters that the demo doesn't cover. Hope that helped! And glad you're enjoying the game despite the issues.