I'm on my M1 14" MacBook Pro, bought in June of 2022.
This is, by far, the best running version of MacOS 26 I have experienced. My Mac feels like it did on Sequoia again, sometimes faster - maybe even close to Sonoma? I was having SO many frame drops, stutters, the works on the previous betas - almost entirely gone. Everything feels like it hits the ProMotion frame rate and smoothness.
Not sure if memory management has been improved too, but having more than 10 windows open across 2 desktops no longer causes miserable slowdowns like it did in betas 1 and 2.
I had noticeably worse battery life and thermals in Beta 2, which is one of the only updates where I've ever seen my fans turn on while idling. Gone in Beta 3.
As a final year college student, I've never had worries about this machine making it through all 4 of my years in school, but I did have concerns about life with it afterwards. Now... maybe I'm naive, but this feels really, really good.