Simply said: Cubase computes all plugins of one channel in one compute thread and thus on one CPU core. If that one core is saturated, the Cubase meter goes into red and you experience dropouts.
This can happen if you have a lot of CPU intensive plugin on one channel, say u-he DIVA as an instrument and then several plugins on the inserts, maybe an amp sim or so.
You can see that in the task manager if you switch the CPU graph to “logical processors” (I think, right click on the graph and see what’s there…).
You can also test it yourself:
- create a new project
- create a new audio track and load several of your most CPU consuming plugins and watch how Cubases’ meter climbs. (compare with task manager)
- now duplicate that track. The audio performance meter should’nt actually increase much.
- repeat the process until suddenly the meter jumps a big step. You’ll notice that you now have one more channel than the number of logical processors on your CPU.
Solution: Don’t use too many resource hungry plugins on one channel. If you cannot avoid that, the only solution I know is to create a group track and route the channel to it and split the plugins across both channel.
btw: if task manager says that Cubase is using 36% but all processes together 60%, that is not good. It could actually be that there is another program running that hogs much of one CPU, and that can lead to problems, too.
The whole system processor usage should not be much higher than that of Cubase.