Hopefully my observations will be helpful to the community:
My rMBP is the top build available (15", 2.7 Ghz, 16gb RAM, 768 Gb Flash Storage). Despite this fact, I'm still experiencing substantial lag. Here are a few details:
- My computer is brand new. (Received it just yesterday).
- It has no other software installed on it whatsoever. .
- It came installed with Mountain Lion (10.8.1). I've since upgraded it to 10.8.2
Despite all of this, I still see a substantial amount of lag when scrolling through webpages - whether on safari or chrome. The lag is particularly noticeable when I hit the "stretch" or "bounce" animation at the top and bottom of any web page - without fail, my computer lags on those animations - and that's without regard to whether the webpages i'm viewing have a lot of content on them or not. .
Setting aside the lag I regularly encounter from the animations, I also see substantial lag when scrolling through webpages with a lot of content (facebook for example). My observation is that my scrolling lags 10-20% of the time on these kinds of pages. In other words if i scroll up and down quickly on theses kinds of webpages, every 5 to 10 times, one of my scroll gestures basically does nothing.
My lag is even further exaggerated if I scroll the webpage after I've zoomed in on it.
Quickly scrolling through webapges like facebook, the activity monitor shows my CPU under 75%-110% load for "Safari Web Content"
Some other important observations:
- Upgrading to 10.8.2 did nothing to improve the scroll lag.
- I observe the same substantial lag even with graphics switchign turned OFF. In other words, even when my comp is using the better graphics card full-time, it still lags.
- I measured for lag in the following scenarios: (10.8.1+ graphics switching ON; 10.8.1 + Graphics swtiching OFF; 10.8.2 + graphics switching OFF; 10.8.2 + graphics switching ON) - lag has been substantial in all 4 scenarios.
- Apple Care advised me to reset the pRAM - no improvement.
- In SAFE MODE - i notice even slower operation, and very glitchy graphics for the dock magnification animation w/ horizontal lines running through them.
To say the least, I'm a little disappointed. A $4,000 laptop shouldn't struggle with something as basic as web browsing. It's my hope that this is something that apple can fix very soon with a software release - otherwise I think a return might be in order.
Thoughts/feedback, welcome.