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Level 3

665 points

Lion and Macs with 4GBs of RAM (or even 8GBs)

There is a consistent theme in various Apple Support Communities, here, and in other hardware and software communities

People with Macs which have 4GBs of RAM are asking, "Why is my Mac so slow under Lion, when it worked fine with Snow Leopard?"

I have suggestions for you if you are considering upgrading to Lion, no matter how much RAM you have, but especially if you have 4GBs or less. Lion uses more RAM, and this may hurt your performance after the move to Lion. You need to plan for this

Check Activity Monitor for Page Outs after you have been using your Mac normally for some hours. If Page Outs are zero or very close to zero, then you'll probably be happy with Lion
If Page Outs are not zero, identify your most commonly used apps which are significant consumers of RAM, and change them so that they run in 32 bit mode, not 64 bits, then reboot
Again, check Activity Monitor for Page Outs after you have been using your Mac normally for some hours. If Page Outs are zero or very close to zero, then you'll probably be happy with Lion
If you are still getting Page Outs, then try running fewer apps concurrently, but only if you can live with this compromise
If you still haven't reduced Page Outs to almost zero, then either stay with Snow Leopard, or upgrade your RAM

FAQ

How do I change an app to 32 bit mode?

Go to your Applications folder, find the app, select it and press Command-i
A window will open titled "applicationname Info" and about half way down you should see "Open in 32-bit mode" with a checkbox beside it. Check it.
If it doesn't say that, then look in this window for "Kind". If it says "Application (PowerPC)", then you have another issue to resolve before upgrading to Lion, because this app will not work under Lion.

How much RAM is enough? And how much time should I spend agonizing over how much to get?

RAM is cheap, so if you don't want to spend a lot of time in decision-making, just add at least 4GBs if it will fit, or 8GBs if you plan to keep the Mac for a while, or bite the bullet and just max it out, unless that would be just too expensive.
If the budget is tight, or the Mac is an older one with limits on RAM, consider 2 GBs an absolute minimum upgrade

Why should I change the apps to 32 bit mode? Why can't Apple "fix this problem" for me?

64 bit mode was introduced to allow apps to exploit large memories. Your Mac is not a large memory Mac. This is not a problem to be fixed by Apple. Use the app in 32 bit mode on a small memory Mac.

But Apple says that Lion needs only 2GBs to work! What's going on here?

It is true that Lion will work in 2GBs. It is not necessarily true that the experience will be enjoyable, unless you run apps which have low RAM demand and run few of them. For example, if you just wanted to run TextEdit alone on a 2GB Mac, you'd probably get great performance under Lion. It's marketing-speak. If you ask me, I'd say that 8GBs is the smallest realistic RAM size for Lion if you prefer a hassle-free experience, and if you can get more, do it.

Why is Lion using up more RAM, this sounds like it is less efficient than Snow Leopard, isn't it?

New releases of operating systems always use more RAM. Why? To save I/Os, to save you time, and to fit new function into your system. Because RAM is cheap and getting cheaper all the time, OS designers are always looking for ways to use more RAM if it will provide a benefit to the end user. What they are doing is optimizing expensive resources, like your CPU, and HDD accesses. And your time! RAM is not an exensive resource.

Hope this helps!

iMac, Mac OS X (10.6.8), 2011 - 27" SSD + HDD 12GB

Posted on Aug 4, 2011 10:13 AM

69 replies

John Kitchen Author

Level 3

665 points

May 16, 2012 8:59 AM in response to dantelo

dantelo

Moving to a 1TB 7200rpm drive will speed up your disk accesses. While you are about it, you might consider choosing an even larger drive for more speed.

Moving from your 320GB drive to a 3TB drive will mean that the access arm will never have to move more than about 10% of way across the disk, and will usually be about 3% of full stroke. This will give you performance similar to a "full" 15K rpm drive.

Another possibility is to use a hybrid drive. I have a Seagate hybrid drive in my MBP and it has transformed it. This drive is a 750GB drive with a few gigs of flash memory. It's a 2.5" drive, so that may not work for you.

But I always believe in maxing out RAM - it's so cheap and can never hurt. I have 16GBs on my iMac and I still get page outs, but in small quantity.

PS The difference in speed between SATA 2 and 3 in the real world is not huge except for very large data transfers. For most I/O, the bulk of the time is taken up in seek (arm movement), and latency (rotation time).

Message was edited by: John Kitchen - added PS

dantelo

Level 1

0 points

May 16, 2012 9:34 AM in response to John Kitchen

I agree about ram, it originally only accepted 4GB DDR, and i maxed it the first month i got it. Now apparently it can take 6GB so will upgrade again. What i don´t understand is why does it only allow 6Gb? if it can read 4gb modules, shouldn´t it do so from both slots and allow 8Gb?

Thanks for the info on the hard drives, I had considered the Hybrids, but they were all 2.5".. and this iMac takes a 3.5". Pitty. I was looking at the Seagate Barracuda 7200.14 with 64mb cache, theres a 2TB version for not much more, would that make a difference? both state the same averages on the description with regards to latency/read/write, etc.

The upgrade is working out fairly cheap,

C2E X7900 2.8Ghz CPU = 80€

4Gb DDR2 (single module) = 45€

1TB 64mb cache HDD = 85€

So for around 210€ i can hopefully keep this iMac for another year or two, and not have to spend a small fortune on a new one. Although a 27" screen would have been nice. I've not opened an iMac before, but i´m not expecting it to be much more complicated than a normal laptop to get to the bits.

May 27, 2012 5:29 PM in response to John Kitchen

Hi John Kitchen,

What a great post. Thank you very much. I think you confirmed my suspicion. I had a 2008 MB (Core 2 Duo) with 4GB Ram and SL. It was not bad at all, but I was running into mostly shortage or physical RAM problems. I am a reasonably high consumer of RAM (hey, all you need is Mail, Firefox and Flash plugin these days!). The MB had served me very well, but as it was getting old, I managed to get a brand new late 2011 13" MBP - with 4GB Ram. I got it from work, and had asked for 8GB, but it came with 4GB. Anyway, after a couple of weeks, I started to wonder if my old Mac was actually performing better than the new MBP. If occassionaly went back to the MB, I would find that it ran pretty sweet.

Anyway, having lived with Activtiy Monitor up for most of the time, I figured it was a RAM issue - however, a bit more painful than the RAM issue I was having on SL. I'm going to upgrade to 16GB, but just before I did that, I googled: "4GB RAM not enough for Lion" and found your marvelous post confirming my suspicions.

Just a note to say thanks, there was some useful suggestions in there too and your responses to other posts have been equally informative. I think your advice is spot on, every time.

Kind regards

Chris H

John Kitchen Author

Level 3

665 points

May 27, 2012 8:02 PM in response to chrishampart

Thank you, Chris, glad to know it has been helpful. I keep Activity Monitor up all the time too. It's obvious that RAM usage is something that "spikes". Same thing happens in Starbucks. One moment the place is empty, the next the line is out the door. No obvious reason, just the random nature of things. For this reason, there is no point in configuring RAM for average conditions, the peaks will kill you!

[Liam]

Level 1

4 points

Oct 25, 2012 6:21 AM in response to John Kitchen

I have a macbook from mid 2009 which according to apple's spec can only support 4GB ram max (I bought it with 4GB as standard 2GB would never be enough). As such, I have not upgraded past snow leopard. I have noticed that my avaliable ram has plumeted after some recent operating system updates. (for example right now I have 1.7GB active, 624MB wired, 1.62 inactive) and 720MB and climbing swap. As I understand it, inacive memory is somewhat like a cache, speeds up recently used files, but isn't that important. I wonder then why does the system use swap in preference to inactive memory?
Interestingly, purge does not seem to clear much of this 'inactive' memory, nor do any command line tools give me any idea who it belongs to.

I am currently running Firefox (10 tabs), iTunes and a text editor, and a pdf open in preview.
Of these Firefox is taking most of the memory. (Firefox 700MB, kernel task 200MB, and mds 110MB are the only things with more than 100MB of ram in activity monitor, next is Finder with 60MB).
Activity monitor is showing all processes and agrees with 'top'.
Right now, my mac is positivly crawling allong, yet the CPU is 80% idle. swithing windows, for example, gives me a beach ball for a few secs. I dont believe this to be a hardware fault as I have run disk, memory benches etc. and all come out fine. also seems to only happen when swap gets toward 1GB or higher.
Is this acceptable for a modern operating system?
Would upgrading to lion (or moutain lion) make things better or worse in your oppinion?

It is obvious that I need more RAM as I usually do quite a lot with the computer (incl developemnt)
Are apple lying about 'max supported ram 4GB'? or am I stuck until I can afford a new computer?

[Liam]

Level 1

4 points

Oct 25, 2012 6:33 AM in response to [Liam]

just ran purge, I now have 1GB of free ram, and my system responiveness is back (still got 1GB inactive though). haven't had much luck with purge in the past, might have to run it more often.

asustud1

Level 1

4 points

Mar 29, 2013 6:22 PM in response to John Kitchen

John,

Your advice below was so helpful for me!!! This truly has "fixed" my memory hogging issues at least as far as I can tell!!! I'll post any updates if they present themself. I'm so glad to have found this post before taking the ultimate plunge back to Snow Leopard due to these memory issues I've been experiencing with only a handful of apps/windows open!!! Thanks again 🙂

Check Activity Monitor for Page Outs after you have been using your Mac normally for some hours. If Page Outs are zero or very close to zero, then you'll probably be happy with Lion
If Page Outs are not zero, identify your most commonly used apps which are significant consumers of RAM, and change them so that they run in 32 bit mode, not 64 bits, then reboot
Again, check Activity Monitor for Page Outs after you have been using your Mac normally for some hours. If Page Outs are zero or very close to zero, then you'll probably be happy with Lion
If you are still getting Page Outs, then try running fewer apps concurrently, but only if you can live with this compromise
If you still haven't reduced Page Outs to almost zero, then either stay with Snow Leopard, or upgrade your RAM

FAQHow do I change an app to 32 bit mode?

Go to your Applications folder, find the app, select it and press Command-i
A window will open titled "applicationname Info" and about half way down you should see "Open in 32-bit mode" with a checkbox beside it. Check it.
If it doesn't say that, then look in this window for "Kind". If it says "Application (PowerPC)", then you have another issue to resolve before upgrading to Lion, because this app will not work under Lion.

John Kitchen Author

Level 3

665 points

Apr 10, 2013 10:32 AM in response to [Liam]

Sorry, this reply may be too late for you, Liam.

I just checked in the (free) MacTracker app, and it says the mid 2009 MacBook will go to 6GBs, so it seems you can remove one 2GB module and replace it with a 4GB module. But not both.

Anyone who has a memory-constrained Mac should check to see if the actual RAM limit is higher than the Apple spec.

I have two Macs, and both of them have more RAM than the Apple spec. This iMac has 32GBs against 16GBs as the standard limit. In some cases, it is possible to go to 2X the Apple number. But not all cases. You must check it out carefully.

Another good source of info is macsales.com

PS since upgrading to 32GBs, I never see any page-outs. Replacing the 16GBs with 32GBs cost less than $100

Message was edited by: John Kitchen to add the postscript

Mar 24, 2014 8:16 PM in response to John Kitchen

wow - you rock John! a birdie found this thread and cross-posted your advice to Evernote forums and i'm a happy camper again on a 2007 MacBook with 3GB of RAM 🙂

Lion and Macs with 4GBs of RAM (or even 8GBs)