Performance/responsiveness is a common concern with new software, especially on older machines. In general, upgrading from Snow Leopard (10.6) to Lion (10.7) wasn't too bad, but now Mountain Lion (10.8) is adding even more features such as Notification Center.

What will be the performance impact of Mountain Lion on Macs which are nearing the lowest end of the system requirements?

  • I'm especially interested in what people using a retina Macbook Pro have to say! ;)
    – gentmatt
    Commented Jul 30, 2012 at 7:19
  • Retina is nowhere near low end ;-) Commented Jul 30, 2012 at 8:18
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    @OP: Posting what your Mac's model is, how much RAM it has etc. would be nice.
    – Nathan
    Commented Jul 30, 2012 at 9:13
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    As the OP I approve all edits that have been made. Truthfully it's not actually my computer that I'm asking about, but "my" in the sense of "someone who may be using an older machine and is concerned about updating to Mountain Lion".
    – jtbandes
    Commented Jul 30, 2012 at 17:42
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    We have a few questions about performance with Lion, I see no reason to close or delete a question about performance with older, lower end computers running Mountain Lion. Commented Jul 30, 2012 at 19:58

12 Answers 12



I have a Mid 2007 iMac 2.4 GHz Intel Core 2 Duo with 4GB RAM. This is the oldest iMac model that can officially run Mountain Lion (according to Apple's tech specs).

I upgraded the first day and haven't noticed any slowdowns so far. Performance actually seems faster in Finder, Mail, Preview, etc.

Safari stands out the most in terms of noticeable speed improvements.


I have a MacBook that I bought in 2009 (2.4GHz Core 2 Duo, 4GB 1067 MHz DDR3), I started with Leopard and had the following experience with upgrades over the past 5 years:

  • Snow Leopard - noticed a performance improvement
  • Lion - noticed significant slow down of all OS X features/applications, was seriously considering buying a new MacBook
  • Mountain Lion - massive speed improvements immediately after upgrade. Start-up time for all applications has improved by a factor of 10, especially for Safari and iTunes. I used to click an application icon and wait for 10 to 30 seconds, now it opens immediately. Obviously, Apple OS X engineers have worked hard to tune and optimise 10.8 for all hardware, even the old the stuff.

Anecdotally, Mountain Lion seems to actually be faster than Lion. There aren't that many new features in Mountain Lion, which means Apple's engineers had more time to analyze and tune its performance. We know, for example, that they specifically optimized Safari scrolling to make it smoother than it used to be. The Versions feature is also faster (or rather, it does more of its work invisibly in the background).

  • Please, what model? RAM and other specifications? Commented Jul 30, 2012 at 8:20
  • My mother made this comment about her Retina MacBook Pro (base model with 16GB RAM). I'm also running it on my 2011 MacBook Air (1.8 GHz i7 with 4GB RAM); it runs very nicely there as well, but I've been using the betas for several months, so I don't have a good feel for how Lion performs anymore. Commented Jul 30, 2012 at 9:09
  • Thanks, both models seem relatively high end. Please don't be offended by the vote down, I think people have simply overlooked the low end point of the question. Commented Jul 30, 2012 at 12:05
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    @GrahamPerrin: Just wondering, are you some type of moderator? As Martín Marconcini has said in another comment, the question didn't exclude newer software and originally was not clear. These answers about newer hardware could be useful to others. Therefore, I have up voted this answer.
    – Nathan
    Commented Jul 30, 2012 at 18:47
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    All users are some kind of moderator — that's what keeps the site working. Everyone is invited to comment, vote, suggest edits, etc. with the goal of getting the best possible questions and answers.
    – Daniel
    Commented Aug 2, 2012 at 13:45

Apple made some improvements to the graphics subsystem, including the OpenGL stuff that can boost performance by up to 10 percent, depending on what you're doing.

Since Snow Leopard, Apple has been relying much more on using the graphics cards in non-traditional roles, including OpenCL, so this sort of performance boost won't just be limited to programs that render 3D. Any app that uses Core Image will get advantages from increased graphics performance, for example Pixelmator, which makes use of the GPU for image editing.


I own a 20" iMac early 2009 with 2 GB RAM and I noticed a significant increase in booting time from previous Snow Leopard.


As a proud owner of one of the slowest Macs that are able to run Mountain Lion (I have an early 2009 model, 2 GB Ram, 2.24 GHz (?) Intel Core 2 Duo and a NVidia 9400M), I have to say that, in contradiction to what I expected, everything is faster, especially when switching desktops. Switching desktops would sometimes lead to some frame drops in Lion, but everything is pretty smooth in ML.

This also applies to other system animations, including the lock icon animation in system preferences, which I have had problems with since Snow Leopard. This might also apply to games, but I haven't really tested that yet. As said by almost everyone, Safari is notably faster to, no scrolling problems whatsoever.

And last but not least is XCode, which builds faster than I remember and doesn't really seem to slow my Mac down anymore.


On my 2010 MacBook Air, I never upgraded to Lion and went directly from Snow Leopard to Mountain Lion, and speed/performance is pretty good. I don't see anything that is much faster (except Safari), but I don't see anything slower either.

Chrome lags scrolling sometimes but I guess that's just a Chrome issue. QuickTime makes my computer slow though when recording the screen (it didn't do that in Snow Leopard).

Safari is a lot faster, especially with the scrolling.

I don't think Mountain Lion would slow up your machine, and as others have said Apple has had more time to tune its performance so if anything it is probably faster than Lion. Animations are relatively faster/smoother too and I haven't seen anything laggy (except when using QuickTime's screen recorder).

I was also worried that Mountain Lion would slow up my computer, but it didn't. :)

  • 2010 Macbook Air is too far from the lowest end of the requirements for 10.8. Commented Jul 30, 2012 at 8:16
  • @GrahamPerrin Um, ok. I didn't see that the OP wanted to know for the lowest end of the requirements. Maybe if the OP posted what type of hardware they have, they'd get a better answer instead of just saying the lowest end of the requirements.
    – Nathan
    Commented Jul 30, 2012 at 9:05
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    I agree with @Nathan the original title (and question) didn't really exclude newer hardware. It requested info "especially" on older hardware, but not ONLY. So I don't think the downvotes are acceptable. Commented Jul 30, 2012 at 15:57
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    Chrome likes memory, lots of it. How much memory does your Air have? Commented Oct 10, 2012 at 5:50

I have an early 2008 iMac with 2.4 GHz Core 2 Duo and 4GB RAM. I have been running lion since it was released last year. I upgraded to mountain lion yesterday and am very happy with the upgrade because, surprisingly, it has actually increased the speed and performance of my computer. The speed I lost from Snow Leopard seems to have returned with Mountain lion.


Faster - I have three macs and I've always found Lion to be quite a bit more resource heavy, hence slower, than snow leopard (enough to be annoying at least). But on installing ML I've found the two machines I've installed on are actually running better than on Snow Leopard.


I have a 2010 MacBook Pro which I upgraded from Snow Leopard. Over the last month everything is running as fast as it was until I run iPhoto. Then the fan starts running overtime, the battery goes flat quickly and everything is slow to respond. I have to reboot before the computer recognizes that iPhoto is no longer running. It is also very hot at this time. iCloud on iPhoto is very slow and I have had to force quit more than once.

On my 2011 24inch Mac which I upgraded from Lion, it is running just as well as before, which was new.


Faster. I upgraded my work MacBook Pro 15" Late 2011, 2.2GHz i7, 8GB RAM, 256GB factory SSD, from 10.6.8 to 10.8.2, and am very happy with overall performance.

Photoshop CS6 screams on this thing.

Remember too that OS upgrades aren't irreversible; use the still-awesome Carbon Copy Cloner or similar to make a complete and bootable snapshot of your system as-is; upgrade; decide if you like the new features and performance..


MacBookPro2,2 | Late 2006 | 15'' 2.16 Ghz Core2Duo (A1211)

  • RAM upgraded to 2 GB,
  • HDD upgraded to 500 GB, WD Green WD5000BEVT-11ZAT0 (silent,green… slow!)

Performance & responsiveness:

  • 10.5 Okay
  • 10.6 Improved clearly to predecessor, very performant! - Optimal OS for that machine.
  • 10.7 Unresponsive, lots of beachballs, and 10-90 (!) seconds later you get the sudden accumulated UI feedback for the queued user interaction stack.
    • Seems to be not a CPU issue, but rather too little RAM and the then stronger utilized virtual RAM on that slow HDD together being the performance bottleneck!
    • 10.7 also uses more animations — of which many can be deactivated, btw — but they seem to be no problem for the GPU ATI Radeon X1600 128 MB in this machine, mostly fluent, a few frame drops every here and then, but not disturbing.
    • Particularly bad app example: Google Chrome is laggy as hell on 10.7. On 10.6 ~5 idle tabs consume about 1-3% CPU, switching is instant, whereas on 10.7 the same current Chrome, even with cleared caches/extensions/etc, lags as hell and utilizes about 30-50% CPU!


  • RAM can be upgradeable to 3GB
  • A SSD could be added internally to the 1.5 Gbit SATA port
  • or into the ExpressCard slot (max capacities marketed are 256GB, and they have lower transfer rates than the current SATA SSDs).


  • Clearly virtual/physical RAM are the issues! With my slightly upgraded configuration (2GB RAM, 500GB HDD), the performance in 10.7 is miserable, I cannot recommend it!
  • Maybe with the maximum pimping possible for this machine (3GB RAM, fast internal SATA SSD), 10.7 could be performant. Any experiences? Appreciated!
  • For now, I will downgrade from 10.7.5 to 10.6.8 again.

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