I just updated my OS from 10.15.5 to 10.15.6. I have two external LG monitors plugged in with HDMI/usb-c cables. When they are connected now the mac becomes very slow. I tried resetting my PRAM and SMC. The resolution on the monitors is 1080p and I tried using scaled resolution. None of the above helped.
My computer:
MacBook Pro 15-inch 2019
Processor 2.4GHz 8 core intel i9
Memory 32 GB 2400 MHz DDR4
Thanks for your help.
MacBook Pro with Touch Bar
Hey alon209,
Thanks for that info and for choosing the Apple Support Communities. If I understand correctly, you are having issues with your Mac running slow when connecting it to 2 external monitors after updating to 10.15.6.
It sounds like you’ve taken some really great troubleshooting steps so far, and I'd be happy to look into this with you.
Does this also occur in a new user account? We'll want to check if there's an issue with any files or settings in the current user account that could be contributing.
Here's how to test in a new user account:
How to test an issue in another user account on your Mac
Also, let's check the steps in the following link:
See how apps affect Mac performance, battery runtime, temperature, and fan activity
You may wish to open Activity Monitor and check the CPU and Memory tabs to see if there is RAM / Memory Pressure and/or if there are runaway applications which are using high amounts of your system’s resources. Open this handy guide for tips on using Activity Monitor:
Cheers.
mac slow with external monitor after os update
