iMac slow after Catalina instal.

Same for me. As dgoodin suggested, I signed out of iCloud and all is back to normal which is better than it has been in a long while. I even suffered this issue before Catalina. I hope Apple can fix this as I do like having iCloud synchronization across my families’ devices.

SOLVED!!

after the disinstallation of malwarebytes my ssd gained 400Mb/s in reading speed. now i have 2300 Mb/s reading and 1400 Mb/s writing. the ssd now has only 100Mb/s less in reading and writing speed compared to mojave.

I will never install app cleaners again...

Yes Antivirus malware really slow things down . Think about it , they scan everything you open . I disconnected from the cloud and that sped things up . I sync my two Macs locally and my three iPads get synced and backed up when I bring them with in range of my WiFi. I depend on both time machine and a large external drive for backing up files.

I run malware bytes on my windows machine just because windows needs protection but it really slows them down too.

app cleaners are a waste and I believe antivirus programs caused more problems and provide false positives just to make you feel protected.

Case in point I have two windows machines that never get on the internet and have no connection to the outside. They just run a shared FileMaker data base. My boss decided we needed antivirus and had me install norton . It immediately said we had viruses. Now how can that be , it’s never (except to get a update from windows) connects to the outside ...

Just wanted to share something I discovered that helped me. Maybe it will help someone else too.

I've been battling slow boot on both of my Mac's (Specs below), immediately after moving to Catalina. I tried reducing the number of startup applications, startup "kext" services (Not sure if this is the right term), clearing cache in various places, etc.

The solution that just worked for me was clearing off my desktop. I saw something on another thread that pointed this out, so figured it was worth a shot! I was trying anything at this point. I had several screenshots, old .dmg installers, random folders, and various other junk on both desktops. Moved these to a different folder elsewhere on my drive, and both Macs immediately started booting quicker. Both were taking a minute or more to boot up. It's now under 20 seconds, probably closer to 10-15 seconds.

Disclaimer: Of course, this isn't a 100% verified solution, but it helped both of my Macs. Definitely something Apple should address.

Computer Specs:

Mac #1

Type: Mac Mini

Model: Late 2012

Processor: 2.6 GHz Quad-Core i7

Memory: 16GB DDR3

MacOS Version: 10.15.2

Drive: 1TB Samsung 960 EVO SSD - 670+ GB free (Upgraded after Catalina install, actually. But, same performance as last drive)

Mac #2

Type: Macbook Pro

Model: 2017 - 13" two thunderbolt ports, no touchbar

Processor: 2.3 GHz Dual-Core i5

Memory: 8GB LPDDR3

MacOS Version: 10.15.2

Drive: 256GB PCIe Flash memory (Installed by Apple) - ~100GB free

Other things to note:

Both Macs have FileVault encryption on

Both Macs have iCloud Desktop sync turned on

Once again, not sure if this will help everyone, but it did help me! Quite significantly, actually.

Thanks so much for this. Removed AVG antivirus and it’s running perfectly. Installed Avast antivirus and it’s still all good. Used AVG for years without issue but it just didn’t let Catalina function. My Mac was minutes away from going through the window 🙂

Late 2013 iMac ran well with Mojave - installed Catalina things started to slow when opening apps. Finally got to where screensaver using Photos album could not open (timed out). After four days of reading these posts and searching the web

(also this issue helped me clean out/move my docs and movies) found a fix:

Remove non Apple or non App Store apps, shut down iCloud Drive (leave iCloud for Photos on). Your stuff stays on iCloud Drive.

Reboot, restart iCloud Drive for all except Desktop and Document folders. (Go to iCloud Drive in the sidebar, create a new documents folder(which you'll be able to move) inside Documents folder(which you can't move) to hold stuff you need on your iMac.

Reinstall desired non Apple apps (in my case Adobe reader), and retrieve new documents folder from iCloud.

I also reloaded Malwarebytes but found it slowed the system response. Uninstalled it and rebooted.

Result: Boot and apps starts still slower than Mojave BUT in app/browser actions seem quicker/smoother.

My screensaver now finds its smart album (last 3 years) and shows our photos when I leave the Mac.

Interestingly no memory or CPU overload ever showed up while investigating why it's running slow.

Catalina is slower than Mojave to open stuff.

Reading 64 bits takes more time than 32 bits?

Thank you so much!! Removing all of the Adobe stuff really seems to have worked! I've tried to turn their stuff off before but the horrid things would always pop up on my processes. This explains why the iMac, even when it was new, seemed to slow ... adobe ...even if adobe isn't fully compatible, for me it seems to have been the primary reason that my iMac was running slow and sluggish. Thank you for telling me what the 'coffee' was :)

I just recently migrated my system that was on a mid 2010 Mac (yes really) onto a 2017 Mac with Catalina installed. Deleting and upgrading a ton of applications in the process obv. I was used to a slow Mac before and was expecting a massive upgrade in speed but now it’s slower then ever. I want to try all the options you recommended but I used adobe photoshop for my work. And unfortunately now you HAVE to download creative cloud and the new Adobe 2020 that’s all on their ****** iCloud system and I have a feeling that’s what’s slowing down my system. My guess is there is no work around except deleting all adobe products that will get my Mac working like yours :/

any suggestions?

If i delete those adobe launchers that you listed, will that mess up my Photoshop? I’m always wary of deleting components of an application...I use the newest adobe photoshop 2020

However you mentioned you still USE photoshop, you just have to re-clean the launch agents each time? So is having a working version of photoshop and a faster running computer possible??

Well I have been having the same issues and finally fixed it. I tried all the suggestions, Spotlight on/off, clear Pram, making radical setup changes and nothing, still ran like a brick.

So I cloned the system from the internal hard drive onto and external StarTech.com hard drive running SSD via the lighting port and its back up to speed.

So basically, the older iMacs must have disc based hard drives and it just can't cope with it.

i started to read the last reply with high hopes... and finally its just about an old hard drive... snif :(

glad you found your problem :D

but i have the same issue (macbook pro late 2013) but i have 16gb of ram and an 512 ssd and Crapalina is showing me her beautiful colorful spinning wheel in finder !!! Chrome has become Internet Explorer 5.0, Adobe Photoshop is now CorelDraw and my macbook pro is now a pc running Vista :( And the best part is that i did a clean install !!! Catastrophic update. Plus all the quicklook plugin arent working anymore...

Thank you!! My 2013 iMac 27 has been very slow since the recent Catalina 10.15.3 update, pinwheels with almost everything. Just saw your fix and deleted my Avira anti-virus and its many related links. My iMac seems to be back to normal. Thanks again for the tip.

My thanks to @TheSubbornGuy. Both Apple and Adobe need to correct their respective products.

I did my own test: I shut down my Adobe Acrobat, and sure enough, the computer is very significantly improved. 

I have Adobe Acrobat Pro DC 2015 for Mac, because I use Acrobat for scanning into ".pdf".  This version of the product has always sucked, when compared to prior versions.  It is a prime example of a Alexander's principle which states that "a mature software product is degraded by each upgrade." (There are "Peter Principle" type reasons for this.) 

I have my own guess regarding the problematic relationship between Adobe products and Catalina OS. The fake solutions borne of echo-chamber ignorance usually point to memory or CPU or a need to do some kind of "clean up;" it's not that. My observations indicate that there has to be something going on with the handling of asynchronous process, or signals, and/or the scheduler, or the such. It has to be something that makes requests upon the OS, and that can then bottle-neck the OS, but doesn't use CPU nor memory.  Something is seizing low level, high priority access to the OS scheduler; which points to i.o. handlers. Catalina is allowing Adobe and other problem processes to displace everyone else's normal access to the scheduler; this is the OS equivalent of a "denial of service" attack.  During the long pauses, the cursor often disappears from the screen; note that the cursor is representative of the mouse, and the mouse is an i.o. device; this strongly suggests the problem has the low interrupt level and high priority of i.o. handling. One seemingly credible commenter said he switched to an SSD and got some relief; disk storage is another form of i.o.

At the practical level, my problem is that I use ".pdf" a lot. Every time I open an old invoice or other ".pdf" document, Acrobat runs. I guess I have to remove Acrobat from my computer (even though I paid for it) and find some free-ware alternative. And what about people who have come to depend on Adobe products, like Photoshop or InDesign, for earning their living; what are they supposed to do?

And why is Catalina allowing itself to be highjacked? A proper OS should protect itself from highjacking.

I wish I had never installed Catalina.

it really helped me a lot... after updating to Catalina my MacBook was painfully slow...none of the apps were responding... word never opened.. Microsoft outlook crashed... PowerPoint was dead.. I was taking ages to login.. then I removed all extensions from chrome.. switched off all notifications... dynamic keyboard and smoother were turned off ,but when I run library/launch agents/com.adobe it made wonders... its much better now..my outlook is back..pdf word all working though not that fast it’s much better. Thanks again