Q: iMac 27" late 2013 3.4ghz i5 8Gb RAM lags every time for more than 5 seconds using Adobe CC Illustrator

By chance do you have FileVault enabled?  Check here >  https://forums.adobe.com/thread/1611990

Otherwise, a Safe Mode boot deletes system caches that may help.

Top left corner of your screen click the  Apple   > Shut Down.

After your Mac shuts down, wait 10 seconds, then press the power button.

Immediately after you hear the startup tone, hold down the Shift key. You should press the Shift key as soon as possible after you hear the startup tone, but not before.

Release the Shift key when you see the gray Apple logo and progress indicator.

Once you are in Safe Mode, go back to the Apple  menu. From the drop down menu click:  Restart

About Safe Mode

You should consider upgrading your ram to 16 or 32GB. Open Activity Monitor while you work in Illustrator and watch your memory pressure Use Activity Monitor on your Mac - Apple Support

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.

You seem very Mac saavy! I have a similar problem with my mid-2011 iMac. Just had an SSD installed and have plenty of memory (12GB), however, I have had 2 episodes today of that darn spinning wheel while working in Illustrator CC. The first time it was several minutes before it stopped. All other Mac apps; Safari PSD, finder, mail are fine. I pasted in some of the info from the log that looked suspect. I'm kinda wondering if it has anything to do with Dropbox. Anyway, hope there's enough here for you to see what's going on. Thanks a bunch.

Ronni

9/5/16 5:08:13.120 PM quicklookd[1238]: Error returned from iconservicesagent: (null)

9/5/16 5:08:57.322 PM pkd[386]: enabling pid=439 for plug-in com.getdropbox.dropbox.garcon(1.21) 6A93DA08-A4F0-4486-9E1F-0FCE97DEA876 /Applications/Dropbox.app/Contents/PlugIns/garcon.appex

9/5/16 5:08:57.349 PM taskgated[496]: no application identifier provided, can't use provisioning profiles [pid=1240]

9/5/16 5:08:57.440 PM garcon[1240]: Failed to connect (colorGridView) outlet from (NSApplication) to (NSColorPickerGridView): missing setter or instance variable

9/5/16 5:08:57.440 PM garcon[1240]: Failed to connect (view) outlet from (NSApplication) to (NSColorPickerGridView): missing setter or instance variable

9/5/16 5:08:57.515 PM iconservicesagent[390]: -[ISGenerateImageOp generateImageWithCompletion:] Failed to composit image for descriptor <ISBindingImageDescriptor: 0x7ff8a8c1a2e0>.

9/5/16 5:08:57.516 PM quicklookd[1238]: Error returned from iconservicesagent: (null)

9/5/16 5:08:57.516 PM iconservicesagent[390]: -[ISGenerateImageOp generateImageWithCompletion:] Failed to composit image for descriptor <ISBindingImageDescriptor: 0x7ff8a8d16180>.

9/5/16 5:08:57.517 PM quicklookd[1238]: Error returned from iconservicesagent: (null)

9/5/16 5:08:57.520 PM iconservicesagent[390]: -[ISGenerateImageOp generateImageWithCompletion:] Failed to composit image for descriptor <ISBindingImageDescriptor: 0x7ff8a8f02a30>.

9/5/16 5:08:57.520 PM quicklookd[1238]: Error returned from iconservicesagent: (null)

9/5/16 5:08:57.521 PM iconservicesagent[390]: -[ISGenerateImageOp generateImageWithCompletion:] Failed to composit image for descriptor <ISBindingImageDescriptor: 0x7ff8a8d126b0>.

9/5/16 5:08:57.521 PM quicklookd[1238]: Error returned from iconservicesagent: (null)

9/5/16 5:08:57.522 PM iconservicesagent[390]: -[ISGenerateImageOp generateImageWithCompletion:] Failed to composit image for descriptor <ISBindingImageDescriptor: 0x7ff8a8c1ba40>.

9/5/16 5:08:57.522 PM quicklookd[1238]: Error returned from iconservicesagent: (null)

9/5/16 5:08:57.523 PM iconservicesagent[390]: -[ISGenerateImageOp generateImageWithCompletion:] Failed to composit image for descriptor <ISBindingImageDescriptor: 0x7ff8a8e120d0>.

9/5/16 5:08:57.523 PM quicklookd[1238]: Error returned from iconservicesagent: (null)

9/5/16 5:08:57.524 PM iconservicesagent[390]: -[ISGenerateImageOp generateImageWithCompletion:] Failed to composit image for descriptor <ISBindingImageDescriptor: 0x7ff8a8f040c0>.

9/5/16 5:08:57.524 PM quicklookd[1238]: Error returned from iconservicesagent: (null)

9/5/16 5:08:57.525 PM iconservicesagent[390]: -[ISGenerateImageOp generateImageWithCompletion:] Failed to composit image for descriptor <ISBindingImageDescriptor: 0x7ff8a8d16180>.

9/5/16 5:08:57.526 PM quicklookd[1238]: Error returned from iconservicesagent: (null)

9/5/16 5:08:57.527 PM iconservicesagent[390]: -[ISGenerateImageOp generateImageWithCompletion:] Failed to composit image for descriptor <ISBindingImageDescriptor: 0x7ff8a8f00500>.

9/5/16 5:08:57.528 PM quicklookd[1238]: Error returned from iconservicesagent: (null)

9/5/16 5:08:57.711 PM garcon[1240]: Connecting to Dropbox on 'com.getdropbox.dropbox.garcon.cafe_501'

9/5/16 5:08:57.713 PM garcon[1240]: Connected to Dropbox on 'com.getdropbox.dropbox.garcon.cafe_501'.

9/5/16 5:08:57.713 PM garcon[1240]: Garcon is ready (1 alive).

9/5/16 5:08:57.714 PM garcon[1240]: Invalidating watch set.

9/5/16 5:08:57.721 PM garcon[1240]: Watch set is now: {(

    file:///Users/ronnivalenti/Dropbox/,

    file:///Users/ronnivalenti/Team%20Dropbox%20(new)

)}.

9/5/16 5:09:01.684 PM garcon[1240]: Garcon destroyed (0 alive).

9/5/16 5:09:01.691 PM garcon[1240]: host connection <NSXPCConnection: 0x7ff15b639840> connection from pid 439 invalidated

9/5/16 5:09:06.731 PM pkd[386]: client 1247 plug-in com.getdropbox.dropbox.garcon election := 1