High CPU usage.. bad Plugins or Cubendo-fault?

There is something which bugs me since years…

Lets say I have a mix project with 150 or more tracks, high plugin load… native, UAD etc…

In the end I often have 80-90% CPU usuage, sometimes a real time export stops because of overload… but when checking the windows task manager Nuendo uses usually only about 25-30% CPU… idle process of my machine 70-75% … CPUs are more ore less equal “filled” - usually not more then 40%.

But Nuendo tells me that my system is at the limit.

Even latest Nuendo 6!

I absolutely dislike that. This MUST have to do something with bad programming of certain plugins OR / and it is a Nuendo problem… I do not know! But it is a PITA to have a top notch machine which is only 25% loaded and you work in a programm which is at the limit.

Check that picture…

VST performance is not only measuring CPU cycles.
It’s a combination of different factors, of which CPU, ASIO strain, and Disc pre-read are just a few.
Trying using a higher ASIO buffer.


I am at 1024 Samples buffer. I can not go higher :slight_smile:

I too have been encountering CPU overload issues with N6-Trial.

The situation is helped by increasing the buffer to 1024 (or even 2048) but then it is impossible to play VST instruments with an external keyboard due to the big latency!

I think my PC is pretty well spec-ed, so what kind of super-machine does one need to run Nuendo properly these days?

I think it would help if someone could put up a specimen session that causes an overload, even if it’s just using stock N6 plugs, so that we can try it on our systems.

I think that N6 is less efficient than N4.3, for example, but there is enough headroom with my PC that it hasn’t been a problem up to now. I work at a buffer of 128.


I’m having these problems even when recording 2 fresh tracks with no plugins or any other audio in the project. I was already at 1024 buffer, so I’ve increased to 2048 to see if that helps. I’ve ruined a few recordings because of chatter that’s introduced into the recording. I can’t have this when I’m recording an important 30-minute interview or doing an ADR session. It’s also just muting audio from time-to-time. My performance meter has usually just quickly peaked. I’m on the latest generation Mac Pro with all the bells and whistles. I never had this problem on N5.5. In fact, it’s been several years and several generations ago since I’ve had this much problems with CPU performance. HELP!

I’m having pretty much the same issues (crackles, stutters and complete audio dropouts for several seconds). I see that you are on a Mac so the problem is not just PC or Mac related - it is a general problem.

Running with a buffer setting any thing above 128 is not possible for me as it makes it impossible to play VST instruments in time, using an external keyboard.

Looking at the VST Performance meter, the Real-time Peak meter is banging up against the red overload bar all the time and the Average Load does the same intermittently (every few seconds).

Mh, well - we are talking about different issues I would say… I do not mean “CPU spikes”… on a two track I usually have only a little CPU usage - depending on the plugins I use… And I am not only talking about N6. I have this in N5.5 as well which I still use most of the time when it comes to bigger mixes…

I am just talking about the difference between Asio-Meter CPU load and Task-Manager CPU load.

I am with Fredo here, but I guess that’s not all.

Though in/out, asio, disk etc will need some CPU (have SSD drives btw) I will be able to run that project with just 1% CPU when I just kick out all plugins, keeping routing, automation etc etc.

Most likely my issues are caused by bad plugin progamming. So it will most likely be not there when using only Nuendo plugins… Just insert the Slate FXG… A real CPU hog… They say that this is because of the awesome audio quality… bullsht!! It uses 30% CPU (Asio meter) while I have only 2 or 3 % CPU more usage in the Task-Manager. Instead of working on that they say “well it is a Mastering Plugin, do not put it on your Mixbus”… Bullsht part two!! Todays Mixes are often mastered “in the mix” - at least here - if not I usually use a “almost there” Mastering chain on the mixbus which enables me to deliver pre-final files which are sounding 90% close to that what I will deliver in the end… Makes mixing way easier.
I would think that this is just bad programming or something like that. In the meantime they announced a new version of that plugin which is re-written for 64 bit as well as it should be “way lighter on the CPU”… if they will not reduce that “awesome audio quality” they have to optimise the code in a way that the same processing needs less CPU.

That’s what I am talking about.

Well, Fredo’s suggestion to just increase the ASIO buffer may be OK when mixing if everything has been bounced to audio, but it does not work when recording midi parts - as the buffer size increases, so does the latency.

All I am saying is that the VST performance meter is a visualisation of a multitude of parameters, of which the two most important are CPU cycles and ASIO strain.
Don’t forget that any (non-VST3) plugin will need some kind of delay compensation. So if a plugin needs -just for the sake of argument- a 1 second buffer, then your system will never run with below a 1 second latency buffer. That’s what the constrain delay compensation button is for, removing all of the delay compensation beefed up by plugins. But as soon as you switch that on (or off, if you like), some of that latency will be compensated for by adding CPU cycles. So it’s a never ending tradeoff between using plugins and operating at very low latencies. And the problem quadruples when you are using 32bit plugins on a 64bit system…

On our systems, we can work on a 32sample latency. But as soon as we reach a dozen tracks, or tracks with a lot of small parts, or when we activate more In’s and out’s, or when we activate a gazillion midi ports, it becomes impossible to run at 32samples.

So if you tell me that you want to have all the lights in the house “on”, all rooms heated to 20°C, the Sauna ready, freezer at the coldest, washing machine running, grilfriend ironing and mother-in-law baking waffles, then I can guarantee you that you’ll very likely will blow the fuses.


In my case I can only repeat: I am at 1024 samples buffer.

I can go 32 samples while recording, even in a 40 track project, but only when I use Nuendo Stock Plugins in addition to some basic minimal premix processing… lets say… a couple of Sonnox/Waves EQs or something like that… I am fine with that, I usually do not use software-monitoring… only when recording some scratch stuff via Guitar Rig or something.

That house sounds great - when can I move in? - If it’s also got a big analog tape machine I’ll be right over!

I take your points. The only 32-bit plugin I use (unless some of the inbuilt Steinberg ones are also 32bit) is NI B4II - I’ll try running without that tomorrow.

No offense …but no.


FREEZE VST Instrument is the answer - I forgot about it!

I’m now down to a buffer size of 96, which is good enough.

Cancel my reservation.