Good day to all. I have a 15" rmbp (mid 2012) with 8 gb RAM and at the moment I have Mavericks as my OS. I am very very very satisfied with Mavericks, I saw a tremendous improvement over Mountain Lion. UI lag that I had with Mountain Lion was completely eliminated, the machine is faster, snappier, with better battery life and very nice memory management. Because of all of the above I was hesitant to make the move towards Yosemite, especially since I was reading a lot of things like UI lag returning to some retina models and of course reports that Yosemite is more RAM hungry than Mavericks and 8 GB RAM might be just not future proof for the OS. So I thought I better wait it out a bit, at least until new firmware updates and refinements are released that perhaps render these above issues (UI lag / responsiveness and memory management) obsolete. So here I am and I am just asking what you good folk of this community think I should do. Are there still people with my kind of machine suffering from UI lag? I am extremely sensitive about this. I hate jerkiness when for example resizing/moving windows or when using spaces etc. And I am also extremely sensitive about memory management. I despise beachballs and constant swapping to occur. My kind of usage is I believe in the middle of a casual user and a pro user. I will browse the net with quite a few tabs (10 or so) due to my work, I will use pages and numbers very often, the occasional (but simple) photoshop job, big collections of photos (using Aperture extensively now - yes I know its gone) the occasional (again simple) video editing thing and movie/music playback. Your help will be highly appreciated. Thanks.