Yes, i3 has inspired me to try yabai on macos. I have configured 6 workspaces and use command + <num(1..6)> to switch to different workspaces.
Most of windows stay in full screen and it's quite better than manually resizing and dragging apps on multiple screens. To move a window to another workspace, just hold on to the top menu bar and press command + workspace number and your window will get moved to that workspace.
You might want to have two separate alerts for this problem, one labelled WARNING and the other CRITICAL, such as 60 percent CPU usage as a warning and 85 percent CPU usage as a critical situation.
You can have two separate SNS Topics for warning and critical alerts. Warning alerts can be thrown to a slack channel and Critical alerts can be configured to invoke the Pager.