Ive installed Audacity on my new iMac 10.15.6 and its really slow … everything is lagging, the editing, playback and so on - I don’t know what to do! Help!
Does your iMac have a 30-bit display? Do Apple menu > About this Mac, then click “System Report”, then click on “Graphics/Displays” in the list on the left. If “Framebuffer depth” says “30-bit Color” then the following may help.
Right-click on the Audacity application icon and choose “Get Info”. In the Get Info window, check “Open in Low Resolution”.
– Bill
This works a treat! 
Perfect solution! Thank you so much - much happier here! 
YYEEESSSS!!! This is exactly what the problem was!! THANK YOOUUU!!! 
Oh thanks so much. That has worked wonders
This looks like a great fix BUT when I right click on the Audacity icon in Finder and I go to Get Info, I do not see the option Open in Low Resolution.
I am on OS Monterrey 12.2.1 Retina display. Has the option moved to some other place?
I since updated to OS 12.5, uninstalled Audacity, and I reinstalled it. Still the option to open in Low Resolution is not listed in the Audacity Info screen. I asked Apple Support, and they say it is something that the App developers have to add.
Was it removed as an option for 3.1.3? Or is there a setting on Mac that makes the option appear?
Apple removed the option in Monterey, but you can still enable it by manually editing the “Info.plist”. See this post: https://forum.audacityteam.org/t/3-1-3-laggy-on-monterey/63863/5
BINGO! That fixed it. Thank you so much!!!
Topic closed as “solved”.
JackieP317’s topic moved to: https://forum.audacityteam.org/t/audacity-lagging-on-new-imac/65795/1