Cubase stutter/pop on stopping playback

I’m having a cpu spike that occurs exactly when I stop playback (but not while playback is playing). When I observe the VST Performance meter, the bars stay nice and low while the music is playing and then spikes to red when I press the spacebar to stop playback (usually the real-time peak meter). This spike is causing a stutter/pop on the audio as it fades when you stop playback (such as midi instruments with long release, reverb tails, delays, etc.).

The CPU spike is an unusual problem as I’m not overloading the project with plugins or midi instruments. Increasing the buffer size helps but the real-time meter is still pushing unusually high. Also, it seems that my synthesizers attribute to the spike more than anything else – synths such as Serum and Absynth. Kontakt seems to be ok. What’s strange is that I can play/stop playback on a section of the project where there are no instruments playing at all, yet it’ll still cause a spike.

I’m currently on a mid-2010 Macbook Pro with Maverick.

I think the culprit might be Serum. I’m reading lots of forums that say it is very high CPU usage. However, it’s still quite odd that the spike happens only at the moment of stopping playback. Not sure why this is happening.

Yep. It’s Serum. I thought it was a Cubase problem but disabling my Serum instances makes the CPU spikes go away. Also, the cpu meter doesn’t shoot up when I stop playback.