Q: iMac become really slow

There is excessive swapping of data between physical memory (that is, the memory chips on the logic board) and virtual memory (one or more files on the startup volume.) That activity is relatively slow and causes the whole system to be less responsive. It can happen for two reasons:

          A long-running process with a memory leak (a kind of bug)

          Not enough memory for your usage pattern

Please note that if the cause is a memory leak, installing more memory will not help. That's likely if you already have more than 4 GB of memory. Tracking down a memory leak can be difficult, and it may come down to a process of elimination.

These instructions are for OS X 10.9 and later. Some details may be slightly different for earlier versions of OS X.

When you notice the swap activity, open the Activity Monitor application and select All Processes from the View menu, if it's not already selected. Select the Memory tab. Click the heading of the Real Mem column in the process table twice to sort the table with the highest value at the top. If you don't see that column, select

          View ▹ Columns ▹ Real Memory

from the menu bar.

If one process (excluding "kernel_task") is using much more memory than all the others, that could be an indication of a leak. A better indication would be a process that continually grabs more and more real memory over time without ever releasing it. Here is an example of how it's done.

The processes named "Safari Web Content" render web pages for Safari. They use a lot of memory and may leak if certain Safari extensions or third-party web plugins are installed. Consider them prime suspects.

Another process often implicated in memory leaks is "inkjet4" or "inkjet8," which is a component of the HP printing software. If it's present, force-quit the process in Activity Monitor to solve the problem temporarily. Empty the print queues in the Printers & Scanners preference pane (which has a slightly different name in each recent version of OS X.) If you don't use an HP printer, reset the printing system. Otherwise, if the problem is recurrent, update the software (which may not help) or contact HP support.

"Wired" memory should be a small part of the total. That memory is not swapped, but it makes less physical memory available which may then result in swapping. If you have a lot of wired memory, that's usually an indication of a memory leak in a third-party program that modifies the operating system at a low level. Ask for guidance in that case.

If you don't have an obvious memory leak, the options are to install more memory (if possible) or to run fewer programs simultaneously.

The next suggestion is only for users familiar with the shell. For a more precise, but potentially misleading, test, run the following command:

sudo leaks -nocontext -nostacks process | grep total

where process is the name of a process you suspect of leaking memory. Almost every process will leak some memory; the question is how much, and especially how much the leak increases with time. I can’t be more specific. See the leaks(1) man page and the Apple developer documentation for details.

Are add-ons a problem in firefox? Do you think this was what was causing it?

If Firefox was leaking memory, and it stopped when you removed the add-ons, then yes.

When you see a beachball cursor or the slowness is especially bad, note the exact time: hour, minute, second.  

These instructions must be carried out as an administrator. If you have only one user account, you are the administrator.

Launch the Console 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.

The title of the Console window should be All Messages. If it isn't, select

          SYSTEM LOG QUERIES ▹ All Messages

from the log list on the left. If you don't see that list, select

          View ▹ Show Log List

from the menu bar at the top of the screen.

Each message in the log begins with the date and time when it was entered. Scroll back to the time you noted above.

Select the messages entered from then until the end of the episode, or until they start to repeat, whichever comes first.

Copy the messages to the Clipboard by pressing the key combination command-C. Paste into a reply to this message by pressing command-V.

The log contains a vast amount of information, almost all of it useless for solving any particular problem. When posting a log extract, be selective. A few dozen lines are almost always more than enough.

Please don't indiscriminately dump thousands of lines from the log into this discussion.

Please don't post screenshots of log messages—post the text.

Some private information, such as your name, may appear in the log. Anonymize before posting.

When you post the log extract, 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 text on Pastebin, then post a link here to the page you created.

A

You installed the "Trovi," "Conduit," or "SearchProtect" ad-injection malware. Follow the instructions on this Apple Support page to remove it.

Back up all data before making any changes.

Besides the files listed in the linked support article, you may also need to remove these files in the same way:

~/Library/Application Support/Firefox/searchplugins/MyBrand.xml
~/Library/Application Support/Google/Chrome/External Extensions/fjadmdmahkpbhgbmmkiiaanlnlekelmn.json
~/Library/Application Support/Mozilla/Extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/deacruzemiliano@outlook.com

Note that when you go to remove the "SearchProtect" app in the Applications folder, you may find instead a subfolder named "SearchProtect" with several apps inside it. Remove that subfolder together with all its contents.

One of the steps in the article is to remove malicious Safari extensions. Do the equivalent in the Chrome and Firefox browsers, if you use either of those. If Safari crashes on launch, skip that step and come back to it after you've done everything else.

If you don't find any of the files or extensions listed, or if removing them doesn't stop the ad injection, then you may have one of the other kinds of adware covered by the support article. Follow the rest of the instructions in the article.

Make sure you don't repeat the mistake that led you to install the malware. Chances are you got it from an Internet cesspit such as "Softonic," "CNET Download," or "SourceForge." Never visit any of those sites again. You might also have downloaded it from an ad in a page on some other site. The ad would probably have included a large green button labeled "Download" or "Download Now" in white letters. The button is designed to confuse people who intend to download something else on the same page. If you ever download a file that isn't obviously what you expected, delete it immediately.

"SearchProtect" may be distributed along with two other applications: "MacKeeper," which is a scam, and "ZipCloud," which, if not actually a scam, has a dubious reputation. Ask if you need instructions to remove those items.

In the Security & Privacy pane of System Preferences, select the General tab. The radio button marked Anywhere  should not be selected. If it is, click the lock icon to unlock the settings, then select one of the other buttons. After that, don't ignore a warning that you are about to run or install an application from an unknown developer.

Still in System Preferences, open the App Store or Software Update pane and check the box marked

          Install system data files and security updates (OS X 10.10 or later)

or

          Download updates automatically (OS X 10.9 or earlier)

if it's not already checked.

B

Back up all data before proceeding.

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

/.Spotlight-V100

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

          Services ▹ Open

from the contextual menu. A folder should open with a subfolder named ".Spotlight-V100" selected. Move the subfolder to the Trash. You may be prompted for your administrator login password.

Restart the computer in safe mode. Certain caches maintained by the system will be rebuilt.

Safe mode is much slower to start up than normal. The next normal startup may also be somewhat slow.

When the login screen appears, restart as usual (not in safe mode) and test. There's no need to log in while in safe mode.

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.

You can't see the folder in the Trash because it's invisible. The next time you empty the Trash, it should be deleted.

C

Although the problem is not the same, please follow the instructions in this support article to reset the Launch Services database. Instead of typing the shell command directed in the article, I suggest that you copy and paste it from the web page into the Terminal window. Make sure you select the whole line. One way to do that is by triple-clicking anywhere in the line.

If you don't already have a current backup, back up all data before proceeding. You may have to log out or restart to see a change.

Take each of these steps that you haven't already tried. Some of them may not be applicable to your model or your situation. Stop when the problem is resolved.

To restart an unresponsive computer, press and hold the power button for a few seconds until the power shuts off, then release, wait a few more seconds, and press it again briefly.

Step 1

The first step in dealing with a startup failure is to secure the data. If you want to preserve the contents of the startup drive, and you don't already have at least one current backup, you must try to back up now, before you do anything else. It may or may not be possible. If you don't care about the data that has changed since the last backup, you can skip this step.

There are several ways to back up a Mac that is unable to start. You need an external hard drive to hold the backup data.

a. Start up from the Recovery partition, or from a local Time Machine backup volume (option key at startup.) When the OS X Utilities screen appears, launch Disk Utility and follow the instructions in this support article, under “Instructions for backing up to an external hard disk via Disk Utility.” The article refers to starting up from a DVD, but the procedure in Recovery mode is the same. You don't need a DVD if you're running OS X 10.7 or later.

b. If Step 1a fails because of disk errors, and no other Mac is available, then you may be able to salvage some of your files by copying them in the Finder. If you already have an external drive with OS X installed, start up from it. Otherwise, if you have Internet access, follow the instructions on this page to prepare the external drive and install OS X on it. You'll use the Recovery installer, rather than downloading it from the App Store.

c. If you have access to a working Mac, and both it and the non-working Mac have FireWire or Thunderbolt ports, start the non-working Mac in target disk mode. Use the working Mac to copy the data to another drive. This technique won't work with USB, Ethernet, Wi-Fi, or Bluetooth.

d. If the internal drive of the non-working Mac is user-replaceable, remove it and mount it in an external enclosure or drive dock. Use another Mac to copy the data.

Step 2

If you've started from an external drive, make sure that the internal startup volume is selected in the Startup Disk pane of System Preferences.

Start up in safe mode. 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 do this. If you don't see the words "Safe Boot" in the startup screen, you haven't started in safe mode. Ask for further instructions.

Safe mode is much slower to start and run than normal, and some things won’t work at all, including wireless networking on certain Macs.

The login screen appears even if you usually log in automatically. You must know the login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.

If the startup progress bar gets stuck for more than a few minutes, or if the system shuts down automatically while the progress bar is displayed, the startup volume is corrupt and the drive is probably malfunctioning. In that case, go to Step 9. If you ever have another problem with the drive, replace it immediately.

If you can start and log in in safe mode, empty the Trash, and then open the Finder Info window on the startup volume ("Macintosh HD," unless you gave it a different name.) Check that you have at least 9 GB of available space, as shown in the window. If you don't, copy as many files as necessary to another volume (not another folder on the same volume) and delete the originals. Deletion isn't complete until you empty the Trash again. Do this until the available space is more than 9 GB. Then restart as usual (i.e., not in safe mode.)

If the startup process hangs again, the problem is likely caused by third-party software that you installed. Ask for further instructions.

Step 3

If the startup process stops at a plain gray screen with a movable cursor, then the login dialog may be active but not visible because of a bug. You might be able to log in by using the arrow keys or the cursor to select the password field and typing your password as usual.

Step 4

If Step 3 fails, the startup volume may be full. If you had previously seen warnings of low disk space, this is almost certainly the case. You might be able to start up in safe mode even though you can't start up normally. Otherwise, start up from an external drive, or else use the technique in Step 1b, 1c, or 1d to mount the internal drive and delete some files. According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation.

Step 5

If a desktop Mac (without a built-in keyboard) hangs at a plain gray screen with a movable cursor, the keyboard may not be recognized. Press and hold the button on the side of an Apple wireless keyboard to make it discoverable. If need be, replace or recharge the batteries. If you're using a USB keyboard connected to a hub, connect it to a built-in port.

Step 6

Sometimes a startup failure can be resolved by resetting the NVRAM.

Step 7

If there's a built-in optical drive, a disc may be stuck in it. Follow these instructions to eject it.

Step 8

Press and hold the power button until the power shuts off. Disconnect all wired peripherals except those needed to start up, and remove all aftermarket expansion cards. Use a different keyboard and/or mouse, if those devices are wired. If you can start up now, one of the devices you disconnected, or a combination of them, is causing the problem. Finding out which one is a process of elimination.

Step 9

Launch Disk Utility in Recovery mode (see Step 1.) Select the startup volume, then run Repair Disk. If any problems are found, repeat until clear. If Disk Utility reports that the volume can't be repaired, the drive has malfunctioned and should be replaced. You might choose to tolerate one such malfunction in the life of the drive. In that case, erase the volume and restore from a backup. If the same thing ever happens again, replace the drive immediately.

This is one of the rare situations in which you should also run Repair Permissions, ignoring the false warnings it may produce. Look for the line "Permissions repair complete" at the end of the output. Then restart as usual.

Step 10

If the startup device is an aftermarket SSD, it may need a firmware update and/or a forced "garbage collection." Instructions for doing this with a Crucial-branded SSD were posted here. Some of those instructions may apply to other brands of SSD, but you should check with the vendor's tech support. 

Step 11

Reinstall the OS. If the Mac was upgraded from an older version of OS X, you’ll need the Apple ID and password you used to upgrade.

Step 12

Do as in Step 11, but this time erase the startup volume in Disk Utility before installing. The system should automatically restart into the Setup Assistant. Follow the prompts to transfer the data from a Time Machine or other backup.

Step 13

This step applies only to models that have a logic-board ("PRAM") battery: all Mac Pro's, MacBooks with a removable main battery, and some others (not current models.) A dead logic-board battery can cause a startup failure. Typically the failure will be preceded by loss of the settings for the startup disk and system clock. See the user manual for replacement instructions. You may have to take the machine to a service provider to have the battery replaced.

Step 14

If you get this far, you're probably dealing with a hardware fault. Make a "Genius" appointment at an Apple Store, or go to another authorized service provider.