CPU Usage Issue with offline bounce in cubase pro 9

Hello all,

I have been facing this weird issue with cubase offline bounce. I am a film and media composer and have a fairly large orchestral template of around 200 tracks, I use Vienna Ensemble and Kontakt and a fair bit of synths. When I start the offline bounce, it starts by showing less time, then the time randomly increases very significantly when i move to any other window such as the finder window or a web browser etc. I then observed the cpu usage with activity monitor, I noticed a lot of dips in the cpu usage when i switch the window, when it starts, the usage is around 45 - 50 % and when i change the wondow it drops to 5 - 6% and the time increases a lot.

Observation 2 : even if I am on cubase all the time, I see a lot of dips in the cpu usage which correspond to the estimated time taken on the bounce.

Anyone experienced this issue before ? I am a bit unsure if I have clicked on a wrong option somewhere, I have not clicked on release Audio engine on the background.

Please help!!!

Thanks and regards