iMac slow and won't startup unless I disconnect backup HD.

[DBM]

Said it all in the title. Also when saving in Photoshop I get the spinning wheel. Once you've elected a place to save it is faster from there on. I suspect the MAC is always looking for another HD. Photoshop only has the MAC HD as a scratch disk. It's generally been slow since upgrading to Catalina.

 

[Cory Cooper]

Hello.

-Which exact Mac?
-What version of OS X/macOS did you upgrade from?
-How much free space is left on the startup/OS drive?
-What version of Adobe Photoshop?

C

 

[DBM]

Hello.

-Which exact Mac?
-What version of OS X/macOS did you upgrade from?
-How much free space is left on the startup/OS drive?
-What version of Adobe Photoshop?

C

iMAC late 2012 1TB. 16GB RAM
From High Sierra
220GB
CC2020

Note: I downloaded and ran ONXY on it and it seems better!

 

[DBM]

I spoke too soon. It still won't boot up with the external HD attached.