Q: Upgrade to OS X 10.8.4 made system slow

See:

Mac Maintenance Quick Assist,
Mac OS X speed FAQ,
Speeding up Macs,
How to Speed up Macs,
Macintosh OS X Routine Maintenance,
Mac troubleshooting: What to do when your computer is too slow,
Essential Mac Maintenance: Get set up,
Essential Mac Maintenance: Rev up your routines,
Maintaining OS X, 
Five Mac maintenance myths and
Myths of required versus not required maintenance for Mac OS X for information.

First, back up all data immediately, as your boot drive might be failing.

There are a few other possible causes of generalized slow performance that you can rule out easily.

• Reset the System Management Controller.
• If you have many image or video files on the Desktop with preview icons, move them to another folder.
• If applicable, uncheck all boxes in the iCloud preference pane.
• Disconnect all non-essential wired peripherals and remove aftermarket expansion cards, if any.
• Check your keychains in Keychain Access for excessively duplicated items.
• Boot into Recovery mode, launch Disk Utility, and run Repair Disk.

Otherwise, take the steps below when you notice the problem.

Step 1

Launch the Activity Monitor 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. Click Utilities, then Activity Monitor in the icon grid.

Select the CPU tab of the Activity Monitor window.

Select All Processes from the menu in the toolbar, if not already selected.

Click the heading of the % CPU column in the process table to sort the entries by CPU usage. You may have to click it twice to get the highest value at the top. What is it, and what is the process? Also post the values for % User, % System, and % Idle at the bottom of the window.

Select the System Memory tab. What values are shown in the bottom part of the window for Page outs and Swap used?

Next, select the Disk Activity tab. Post the approximate values shown for Reads in/sec and Writes out/sec (not Reads in and Writes out.)

Step 2

If you have more than one user account, you must be logged in as an administrator to carry out this step.

Launch the Console application in the same way you launched Activity Monitor. Make sure the title of the Console window is All Messages. If it isn't, select All Messages from the SYSTEM LOG QUERIES menu on the left. If you don't see that menu, select

View ▹ Show Log List

from the menu bar.

Select the 50 or so most recent entries in the log. Copy them to the Clipboard (command-C). Paste into a reply to this message (command-V). You're looking for entries at the end of the log, not at the beginning.

When posting a log extract, be selective. Don't post more than is requested.

Please do not indiscriminately dump thousands of lines from the log into this discussion.

Important: Some personal information, such as your name, may appear in the log. Anonymize before posting. That should be easy to do if your extract is not too long.

I have the exact same laptop as well as same issue on the same day. I re-installed my system software and noticed that the system still lagged even while booted off of system drive as well as in safe mode!

The kernel is using excessive processor cycles. Below are some possible causes for this condition.

Throttling

When it gets high temperature readings from the hardware, or a low-voltage reading from the battery, the kernel may try to compensate by interrupting the processor(s) to slow them down and reduce power consumption. This condition can be due to

• a buildup of dust on the logic board
• high ambient temperature
• a worn-out or faulty battery in a portable
• the malfunction of a cooling fan or sensor

Note that if the problem is caused by a sensor, there may be no actual overheating or undervoltage.

If the computer is portable, test with and without the AC adapter connected. If kernel_task hogs the processor only on battery power, the fault is in the battery or the logic board.

The Apple Hardware Test or Apple Diagnostics, though not very reliable, is sometimes able to detect a bad fan or sensor.

Installed software

User-installed software that includes a device driver or other kernel code may thrash the kernel. That category includes virtualization software, such as Parallels and VMware, as well as most commercial "anti-virus" products. Some system-monitoring applications, such as "iStat," can also contribute to the problem. You can test for this possibility by completely disabling or removing the software according to the developer's instructions, or booting in safe mode. Note, however, that disabling a system modification without removing it or booting in safe mode may not be as easy as you think it is.

Corrupt NVRAM or SMC data

Sometimes the problem is cleared up by resetting the NVRAM or the SMC.

Peripherals

Connecting an external display to some MacBook Pro models via Thunderbolt may cause this issue. I don't know of a fix, other than to disconnect the display.

Encryption

Transferring large amounts of data to or from an encrypted disk image or FileVault volume may put an extra load on the kernel. If both the source and the destination are encrypted, the load may be doubled. If you transfer data from an encrypted disk image on an encrypted partition to another such image on another encrypted partition, the load may be quadrupled.

This issue probably doesn't affect late-model Macs with an Intel i-series, recent Xeon, or later processor. Those processors support hardware-accelerated encryption. You can determine what kind of processor you have by selecting About This Mac from the Apple menu in the menu bar.

I've been watching this thread since I have same problem, same computer and happened on same day. My system still lags off of boot startup and safe mode. Wouldn't that mean that it's not hard drive or third party software related? I was wondering if something in the last update could have changed something at the kernel level? Is there a way to revert the whole system to factory (not just wiping and clean installing)?

Try quitting one of thge applications and see if there is a change.

Uninstall them one at a time and test.

Even though I'm being completely ignored. As mentioned we have same model.. broke same day.. same problem. I took mine in on Monday. I would suggest starting off of boot.. (ctrl-R) and see if it's still slow like mine was. If so, then obv it's not your installed software.