iMac excessive memory pressure due to an email?

In the Advanced settings for the mail account, uncheck the box marked

Send large attachments with Mail Drop

if it's checked. If you have more than one account, repeat with each one. Relaunch Mail and test.

1. This procedure is a diagnostic test. It changes nothing, for better or worse, and therefore will not, in itself, solve the problem. But with the aid of the test results, the solution may take a few minutes, instead of hours or days.

The test works on OS X 10.7 ("Lion") and later. I don't recommend running it on older versions of OS X. It will do no harm, but it won't do much good either.

Don't be put off by the complexity of these instructions. The process is much less complicated than the description. You do harder tasks with the computer all the time.

2. If you don't already have a current backup, back up all data before doing anything else. The backup is necessary on general principle, not because of anything in the test procedure. Backup is always a must, and when you're having any kind of trouble with the computer, you may be at higher than usual risk of losing data, whether you follow these instructions or not.

There are ways to back up a computer that isn't fully functional. Ask if you need guidance.

3. Below are instructions to run a UNIX shell script, a type of program. As I wrote above, it changes nothing. It doesn't send or receive any data on the network. All it does is to generate a human-readable report on the state of the computer. That report goes nowhere unless you choose to share it. If you prefer, you can act on it yourself without disclosing the contents to me or anyone else.

You should be wondering whether you can believe me, and whether it's safe to run a program at the behest of a stranger. In general, no, it's not safe and I don't encourage it.

In this case, however, there are a couple of ways for you to decide whether the program is safe without having to trust me. First, you can read it. Unlike an application that you download and click to run, it's transparent, so anyone with the necessary skill can verify what it does.

You may not be able to understand the script yourself. But variations of it have been posted on this website thousands of times over a period of years. The site is hosted by Apple, which does not allow it to be used to distribute harmful software. Any one of the millions of registered users could have read the script and raised the alarm if it was harmful. Then I would not be here now and you would not be reading this message. See, for example, this discussion.

Another indication that the test is safe can be found in this thread, and this one, for example, where the comment in which I suggested it was recommended by one of the Apple Community Specialists, as explained here.

Nevertheless, if you can't satisfy yourself that these instructions are safe, don't follow them. Ask for other options.

4. Here's a general summary of what you need to do, if you choose to proceed:

☞ Copy a particular line of text to the Clipboard.

☞ Paste into the window of another application.

☞ Wait for the test to run. It usually takes a few minutes.

☞ Paste the results, which will have been copied automatically, back into a reply on this page.

These are not specific instructions; just an overview. The details are in parts 7 and 8 of this comment. The sequence is: copy, paste, wait, paste again. You don't need to copy a second time.

5. Try to test under conditions that reproduce the problem, as far as possible. For example, if the computer is sometimes, but not always, slow, run the test during a slowdown.

You may have started up in safe mode. If the system is now in safe mode and works well enough in normal mode to run the test, restart as usual. If you can only test in safe mode, do that.

6. If you have more than one user, and the one affected by the problem is not an administrator, then please run the test twice: once while logged in as the affected user, and once as an administrator. The results may be different. The user that is created automatically on a new computer when you start it for the first time is an administrator. If you can't log in as an administrator, test as the affected user. Most personal Macs have only one user, and in that case this section doesn’t apply. Don't log in as root.

7. Load this linked web page (on the website "Pastebin.") The title of the page is "Diagnostic Test." Below the title is a text box headed by three small icons. The one on the right represents a clipboard. Click that icon to select the text, then copy it to the Clipboard on your computer by pressing the key combination command-C.

If the text doesn't highlight when you click the icon, select it by triple-clicking anywhere inside the box. Don't select the whole page, just the text in the box.

8. Launch the built-in Terminal application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

Click anywhere in the Terminal window to activate it. Paste from the Clipboard into the window by pressing command-V, then press return. The text you pasted should vanish immediately.

9. If you see an error message in the Terminal window such as "Syntax error" or "Event not found," enter

exec bash

and press return. Then paste the script again.

10. If you're logged in as an administrator, you'll be prompted for your login password. Nothing will be displayed when you type it. You will not see the usual dots in place of typed characters. Make sure caps lock is off. Type carefully and then press return. You may get a one-time warning to be careful. If you make three failed attempts to enter the password, the test will run anyway, but it will produce less information. If you don't know the password, or if you prefer not to enter it, just press return three times at the password prompt. Again, the script will still run.

If you're not logged in as an administrator, you won't be prompted for a password. The test will still run. It just won't do anything that requires administrator privileges.

11. The test may take a few minutes to run, depending on how many files you have and the speed of the computer. A computer that's abnormally slow may take longer to run the test. While it's running, a series of lines will appear in the Terminal window like this:

[Process started]

Part 1 of 8 done at … sec
…
Part 8 of 8 done at … sec

The test results are on the Clipboard.

Please close this window.

[Process completed]

The intervals between parts won't be exactly equal, but they give a rough indication of progress. The total number of parts may be different from what's shown here.

Wait for the final message "Process completed" to appear. If you don't see it within about ten minutes, the test probably won't complete in a reasonable time. In that case, press the key combination control-C or command-period to stop it and go to the next step. You'll have incomplete results, but still something.

12. When the test is complete, or if you stopped it because it was taking too long, quit Terminal. The results will have been copied to the Clipboard automatically. They are not shown in the Terminal window. Please don't copy anything from there. All you have to do is start a reply to this comment and then paste by pressing command-V again.

At the top of the results, there will be a line that begins with the words "Start time." If you don't see that, but instead see a mass of gibberish, you didn't wait for the "Process completed" message to appear in the Terminal window. Please wait for it and try again.

If any private information, such as your name or email address, appears in the results, anonymize it before posting. Usually that won't be necessary.

13. When you post the results, you might see an error message on the web page: "You have included content in your post that is not permitted," or "The message contains invalid characters." That's a bug in the forum software. Please post the test results on Pastebin, then post a link here to the page you created.

14. This is a public forum, and others may give you advice based on the results of the test. They speak for themselves, not for me. The test itself is harmless, but whatever else you're told to do may not be. For others who choose to run it, I don't recommend that you post the test results on this website unless I asked you to.

______________________________________________________________

Copyright © 2014, 2015 by Linc Davis. As the sole author of this work (including the referenced "Diagnostic Test"), I reserve all rights to it except as provided in the Use Agreement for the Apple Support Communities website ("ASC"). Readers of ASC may copy it for their own personal use. Neither the whole nor any part may be redistributed.

You removed the paste before I saw it.

When you ran the test, there was no unusual memory pressure, so I can't be sure of identifying the cause of the problem.

A

Some of your user files (not system files) have incorrect permissions or are locked. This procedure will unlock those files and reset their ownership, permissions, and access controls to the default. If you've intentionally set special values for those attributes, they will be reverted. In that case, either stop here, or be prepared to recreate the settings if necessary. Do so only after verifying that those settings didn't cause the problem. If none of this is meaningful to you, you don't need to worry about it, but you do need to follow the instructions below.

Back up all data before proceeding.

Step 1

If you have more than one user, and the one in question is not an administrator, then go to Step 2.

Enter the following command in the Terminal window in the same way as before (triple-click, copy, and paste):

sudo find ~ $TMPDIR.. -exec chflags -h nouchg,nouappnd,noschg,nosappnd {} + -exec chown -h $UID {} + -exec chmod +rw {} + -exec chmod -h -N {} + -type d -exec chmod -h +x {} + 2>&-

You'll be prompted for your login password, which won't be displayed when you type it. Type carefully and then press return. You may get a one-time warning to be careful. If you don’t have a login password, you’ll need to set one before you can run the command. If you see a message that your username "is not in the sudoers file," then you're not logged in as an administrator.

The command may take several minutes to run, depending on how many files you have. Wait for a new line ending in a dollar sign ($) to appear, then quit Terminal.

Step 2 (optional)

Take this step only if you have trouble with Step 1, if you prefer not to take it, or if it doesn't solve the problem.

Start up in Recovery mode. When the OS X Utilities screen appears, select

Utilities ▹ Terminal

from the menu bar. A Terminal window will open. In that window, type this:

resetp

Press the tab key. The partial command you typed will automatically be completed to this:

resetpassword

Press return. A Reset Password window will open. You’re not going to reset a password.

Select your startup volume ("Macintosh HD," unless you gave it a different name) if not already selected.

Select your username from the menu labeled Select the user account if not already selected.

Under Reset Home Directory Permissions and ACLs, click the Reset button.

Select

 ▹ Restart

from the menu bar.

B

Back up all data.

Run the following command in the same way as before. It moves to the Trash "semaphore" files that have not been cleaned up by the system and may be interfering with normal operation. The files are empty; they contain no data. There will be no output this time.

find L*/{Con*/*/Data/L*/,}Pref* -type f -size 0c -name *.plist.??????? -exec mv {} .Trash/ \; 2>&-

Log out or restart the computer and empty the Trash.

C

Back up all data before proceeding.

Launch the Font Book application and validate all fonts. You must select the fonts in order to validate them. See the built-in help and this support article for instructions. If Font Book finds any issues, resolve them.

Start up in safe mode to rebuild the font caches. Restart as usual and test.

Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t start in safe mode. In that case, ask for instructions.

If you still have problems, then from the Font Book menu bar, select

File ▹ Restore Standard Fonts...

You'll be prompted to confirm, and then to enter your administrator login password.

Also note that if you deactivate or remove any built-in fonts, for instance by using a third-party font manager, the system may become unstable.

D

Delete "MemoryClean," which is at best useless.

E

Although it's probably not related to your problem, that model was the subject of a warranty extension for defective video cards:

iMac (27-inch): AMD Radeon 6970M Video Card Replacement Program - Apple Support

F

In the Accessibility preference pane, turn off cursor magnification and see whether there's an improvement.

G

Some OS X files (Installer package receipts) are missing or invalid. Other OS files may also be missing or invalid.

If you don't already have a current backup, back up all data, then reinstall the OS.* You don't need to erase the startup volume, and you won't need the backup unless something goes wrong. If the system was upgraded from an older version of OS X, you may need the Apple ID and password you used.

There are ways to back up a computer that isn't fully functional. Ask if you need guidance.

If you installed the Java runtime distributed by Apple and still need it, you'll have to reinstall it. The same goes for Xcode. All other data will be preserved.

*The linked support article refers to OS X 10.10 ("Yosemite"), but the procedure is the same for OS X 10.7 ("Lion") and later.

H

A couple of obsolete iLife components are present and should be removed.

Back up all data before proceeding.

Triple-click anywhere in the first line below on this page to select it:

/Library/QuickLook/GBQLGenerator.qlgenerator

/Library/Spotlight/GBSpotlightImporter.mdimporter

Right-click or control-click the highlighted line and select

Services ▹ Reveal in Finder (or just Reveal)

from the contextual menu.* A folder should open with an item selected. Move the selected item to the Trash. You may be prompted for your administrator login password.

Repeat with the second line.

Restart the computer and empty the Trash.

*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination command-C. In the Finder, select

Go ▹ Go to Folder...

from the menu bar and paste into the box that opens by pressing command-V. You won't see what you pasted because a line break is included. Press return.

I

If there's no improvement after all the above steps, remove the Xbox 360 driver.

Any third-party software that doesn't install from the App Store or by drag-and-drop into the Applications folder, and uninstall by drag-and-drop to the Trash, is a system modification.

Whenever you remove system modifications, they must be removed completely, and the only way to do that is to use the uninstallation tool, if any, provided by the developers, or to follow their instructions. If the software has been incompletely removed, you may have to re-download or even reinstall it in order to finish the job.

I never install system modifications myself, and except as stated in this comment, I don't know how to uninstall them. You'll have to do your own research to find that information.

Here are some general guidelines to get you started. Suppose you want to remove something called “BrickMyMac” (a hypothetical example.) First, consult the product's Help menu, if there is one, for instructions. Finding none there, look on the developer's website, say www.brickmymac.com. (That may not be the actual name of the site; if necessary, search the Web for the product name.) If you don’t find anything on the website or in your search, contact the developer. While you're waiting for a response, download BrickMyMac.dmg and open it. There may be an application in there such as “Uninstall BrickMyMac.” If not, open “BrickMyMac.pkg” and look for an Uninstall button. The uninstaller might also be accessed by clicking the Customize button, if there is one.

Back up all data before making any changes.

You will generally have to restart the computer in order to complete an uninstallation. Until you do that, there may be no effect, or unpredictable effects.

If you can’t remove software in any other way, you’ll have to erase and install OS X. Never install any third-party software unless you're sure you know how to uninstall it; otherwise you may create problems that are very hard to solve.

Trying to remove complex system modifications by hunting for files by name often will not work and may make the problem worse. The same goes for "utilities" such as "AppCleaner" and the like that purport to remove software.