Q: El Capitan running slowly?

11.10.2 update failed during download for me.  I guess my next try is a fresh install install of Yosemite as suggested by KIMBAKAT.

mid 2010 iMAC 27" that passed AHT....

The fact that you had trouble updating to 10.11.2 would indicate that you have problems with your computer not with El Capitan.

I have El Capitan on a Macbook Air 2013 and that runs smoothly. So I thought I could easily install El Capitan on my iMac 2012. That was a disaster! Nothing worked and the super fast Imac turned very very slow. I downgraded to Yosemite with Time Machine, cleared all log files, restarted but Mac, did a Nvpram reset and that still did not help. Finally, after searching many posts, I deleted all extensions in Safari. And yes, that did the trick. Maybe it will help you too.

El Capitan *****! I upgraded only because Adobe had me over a barrel and in order to get photoshop cc I had no choice but to upgrade. I'm a graphic designer and I use my computer for a living. I go on the clock when working and am expected to have jobs done in a reasonable amount of time. Because of El Capitan, I have to revert to my old macbook version 10.6.8. It actually runs faster!! Is that a joke or what? Take my advice and don't upgrade to El Capitan. No matter what Apple Support tells you, none of their so-called solutions will help you computer run faster.

I created a user like you said and everything worked like how it should. Any tips on what to look for that could be causing my machine to go turtle speed?

This worked for me:

Open Mail (even though it takes for ever!)

Click on Window tab at top

Click on Connection Doctor

Click on Show Logs

Select all (including the zip files) and put in trash.

It was after I moved the zip files to trash that it started behaving and I'm back up to speed now.  So it seems the activity that was taking so much memory was in the zip file creation.

After making these two changes, my 2010 iMac is cruising.. no more BeachBall issues.

1. Uncheck the 'Log Connection Activity' in Mail -> Window -> Connection Doctor

2. Click on 'Show Logs' (next to the 'Log Connection Activity') will open the folder in Finder. Delete all files in the folder. 'Quit' Mail and open it back..

Problem solved for me..

INOPERABLE IMAC AFTER UPGRADE SOLVED!!!!! UNCHECK ALL ITEMS ON SPOTLIGHT PREFERENCES.

Well, past weeks have been a nightmare after upgrading to El Capitan. I have a 20111 imac 27", it has gone from super fast to basically inoperable, even running Clean My Mac 3 every half an hour...memory usage was going from 12Gb to 1 in a matter of clicks, everything would freeze, even icons would not show anymore, thats how slow it had gone. Last night reading this forum, I decided to give it a go to some suggestions, I reset the SMC by umplogging it from powers for a few seconds, and ran a full scan with Clean My Mac, restarted, seemed slightly faster. This morning I went on system preferences/spotlight and unchecked everything, why do I need this bloody thing indexing files anyway? Cant I remember where they are? so...surprise surprise, my mac is super fast again after unchecking every single item on spotlight settings. This may help everyone out there in need for urgent help like i was.

Good luck.

My brand new iMac was purchased in October (late 2015 model) and just up until yesterday was performing perfectly, then I got the spinning beach ball problem.  After reading the latest replies, I unchecked three quarters of the spotlight preferences as suggested by rcezar and voila the spinning ball has gone.  What I am puzzled about is why it happened when it did.  I checked my El Capitan updates and found it was updated to 10.11.2 on Dec 15th.  My problems did not start until yesterday, 17th.

Anyway, so far, so good!  Thank you rcezar!

that is awesome malonefromtallahassee, Im very pleased it has helped you too. I dont give a **** if my mac finds everything for me, i can do it myself when I need to...as long as it is usable!!! and man it was absolutely slow like ****. as to why it only started a few days ahead, it happened to me too, i think it takes a while for it to go downhill after the upgrade. I am sure it has something to do with spotlight, as we are both proof of it. Cheers!

FOLLOW UP ON MY LAST POST:

"INOPERABLE IMAC AFTER UPGRADE SOLVED!!!!! UNCHECK ALL ITEMS ON SPOTLIGHT PREFERENCES."

hey guys, before we run into some kind of misunderstandings, i wanted everyone to remember that if you uncheck all or many of the spotlight items on system preferences/spotlight, it WILL SOLVE THE ISSUE AT THE EXPENSE OF SPOTLIGHT...

the spotlight search will no longer find your files when you type them in the search if you go ahead an uncheck the items in its preferences like I did...so it is a trade until they fix this thing hey...either you have a mac you cant use or your search will not work. I know which one I chose and would do it again if i had to!!! good luck!!!

Weeell, not quite!  Spinning ball is back - dammit.  I also tried rb21's solution, deleting mail logs.  Still getting the ball.  Not quite as bad as before, computer is useable but it reminds me of the old 'watching paint dry' internet connections.  As I have free support at the moment, I contacted Apple and basically we decided  that I should not use a certain screensaver.  It did not do the trick, so I have to call them again.  Will update.

Having installed El Capitan plus the latest update then like everyone else I have just been watching beachballs...ever present,constant companion beachballs....I have also been constrained to read through all of these posts in an effort to try and understand,even vaguely, what exactly has happened to my Macbook Pro (2014) and iMac (2012) which grinds to a complete halt for minutes at a time even when opening a new page...please could you explain to an absolute un-tech savvy person (i.e. someone who spent all that money in the belief that I would get a hassle free product) HOW to access "connection doctor" and delete Mail log....

In the course of having to read all these posts I have found the activity monitor and can see a highish CPU usage next to the Mail icon...not sure if it will help but  am willing to try and learn how to fix this as I am currently stuck with two pieces of very expensive junk...I've left out all the swearing...suffice to say I am disappointed and frustrated beyond words

Hi @Burnin' Coal do what some here have suggested. If the issue is mail, go to system preferences and uncheck or delete your accounts one by one. This seems to work for many of us. My imac is like new for more than a week after i unselected all of the spotlight items though, some have said it doesnt work.

i guess it is a case to case issue unfortunately.

Thanks rcezar...I have already deselected stuff I never use in Spotlight...still slow...will try wiping accounts tomorrow as this has been a (very VERY unwelcome) baptism of fire for me with regard to technical stuff...I mean come on - if this computer was a car I'd be taking it back to the dealer and say "fix it" whereas the Apple approach would appear to be to tell you to talk to other people with the same problem then you got to roll your sleeves up and fix it yourself...very unimpressed