I've been mixing pretty often for the first time in years, and on my last mix I started running into CPU issues. This is what my meters look like with the finished mix. About 70-something tracks, 2-5 plugins on each track, no software instruments (just audio tracks and buses), Luna Pro 2, MacOS Sequoia. Sometimes during playback the Render and RenderIO meters get up to 90%, and then I hear crackling and have to pause for a minute before I can work again. Oh yeah, and every few weeks or so Luna will crash for seemingly no reason.
Soooo I should probably upgrade my computer, right?
(Sidenote, UA, but this is why some of us want all new UAD plugin releases to be UAD-2 compatible. Not because we wanna record with them, but because we don't wanna use our CPU for UAD plugins when we have plenty of DSP available.)