ForumsSoftware ← CPU Spikes on Macbook Pro (early2015) Retina 16GB

i have loads of cpu spikes on my macbook pro and bitwig studio....
running plugs like diva or diversion which are cpu hungry run smoothly,,,, aalto is spiking as soon as i choose a preset from the menu

there were some problems reported with some recent MBP - I think Randy fixed these, so you might want to see if you have the same issue with the betas Randy has recently posted.

happens as well with the new betas...

Can you send me more detailed info? Here or email is fine too. With my setup I can no longer reproduce anything I'd call "CPU spikes" here, so please send

  • OS and software versions
  • specific steps to reproduce, starting from empty Bitwig doc if possible
  • what specific symptoms you see or hear


Hello, just created an user to reply here.
I'm a user of the demo version, just downloaded latest demo version (1.08) and i have heavy spikes.
here's a screenshot of the environment right now:
i'm using logic pro x, with everything else closed (nothing else running on the computer)
macbook pro retina 13 inch (early 2015), 8 gb ram, 256 ssd hard drive.
if i open one instance of aalto cpu level in logic climb to 100% and stay there all along. if i just open a polyphonic patch it creates crackles in the audio,after a few minutes the cpu level decreases and the crackle stops.
if i open two instances everything becomes more evident. the crackling stops if i start using a bigger latency (256 onwards) but it find hard to use it in a big project with other plugins running if it crackles so easily.
my soundcard is an universal audio apollo 8 (thunderbolt, latest version) so really everything should be running really smoothly.

hope this helps. thanks!

@enparticular: thanks for the report. Can you tell me what speed of CPU you have in your Early 2015 13" Macbook Pro?

I have exactly three reports of weird glitches, and all with this particular Macbook Pro. It's very mysterious.

Please try opening some patch that just makes noise by itself (Alessandro's Machines for example) then closing the plugin window. Does the problem get better / CPU use go down without the graphics showing?

Can you please try Kaivo and Virta and let me know if you have similar issues?

@randy it's a 2.7 GHz Intel Core i5.
i just did some more testing:

  • disabling the visual interface does little to change the performance
  • waiting some time definately helps
  • it's not based on patch complexity but more in polyphony. opening the default patch and changing the voices from 2 to 4 makes the cpu go to 99%. then it goes down a bit, but with spikes.

i will try kaivo and virta later and let you know.

ok! downloaded kaivo and virta:

OK, Let's focus on Aalto then. the other plugs take a lot of CPU even when they are functioning properly, so the problem will be much more obvious with Aalto. It looks like one voice of Virta is taking up 25% of CPU or something in your example, which is too much. But 10% or so would not be out of line.

For more background on CPU use in the plugins please see
You may find some tips that help. They are expected to take up significant CPU when no notes are playing, for example.

back to Aalto, here's a question: when you load Aalto does the CPU meter seem to go up gradually?

Thanks for the assistance. if you are willing to hang around and try some of my experiments I'll be happy to give you a coupon in appreciation.

ey, sure.
i recorded a video of the behaviour of the plugin when it loads. i'll send it to you to randy (at)

ey, sure.
i recorded a video of the behaviour of the plugin when it loads. i'll send it to you to randy (at)

Hello Randy,
I too am having big CPU meter increase with the new Aalto 1.8.1b1 (AU and VST).
I am also using a MacBook Pro Retina 13" early 2015, running El Capitan 10.11.6.
I am using it within Ableton Live. When I open Live with nothing in a set, my CPU meter sits at 2%. As soon as I drop Aalto on a MIDI track, with the Default preset, it jumps to 40-44%...the meter moves between those percentages. When I switch to one of the Alessandro's Machines presets, some of them lower the CPU in the 18-30% range. Then, when I switch back to the Default preset, it then hovers between 20-24%. I tried the Richard Devine 'Mechanics' presets and thy vary from 18%-45% depending on the preset. It's odd that the Aalto Default is always in the 40% range as soon as I put Aalto on a track, but is then lower after I switch back to it from another preset.
Please know I love Aalto and am not sharing this to complain---but rather to keep you in the loop. Thanks for your brilliant work!

Hi, I appreciate the feedback. Can you tell me what CPU you have in your MacBook Pro?

2.7 GHz Intel Core i5
8GB Ram

I can't test it on the affected machines, so I'm not too hopeful. But if my hunch is right, this beta may make things better.

just testing it, sorry to say it but behaviour is just the same :-/

OK, I just ordered a refurbished 13" RMBP Early 2015 from Apple. I can pick it up in a few days and hopefully reproduce this then.

that's what i'd call a really dedicated developer. :) i'm not affected by this, but i hope you can reproduce the bug on the coming macbook, randy.

I have the Early 2015 MacBook Pro on my desk now. It came with MacOS 10.12.1. I've done the following:

  • downloaded and installed Ableton Live
  • downloaded and installed Aalto

pulling up Ableton and making one instance of Aalto, the builtin patch "aalto default" comes up with four voices, taking 20% of CPU as measured in Live's meter. I can play some notes on the computer keyboard and I'm not getting glitches. Playing notes or resting, the meter is at 20-22%, which is what I would expect. Turning the number of voices down to 1, the meter is at 6–7%.

I'll try downloading Logic, updating the OS and doing some more tests, and see what I can do to reproduce the glitches.

In any case, I like this notebook alright. It has two USB-A ports and an escape key!

Updated the OS to the latest 10.12.2, no issues there.

Downloaded Logic Pro 10.2.4. Make an empty Software Instrument project. Add one instance of Aalto—and boom! crazy CPU spikes and glitches. I am seeing all the symptoms that @enparticular has been reporting. It's worse with the plugin window open, but plenty bad without it as well.

So now I'm downloading Xcode. I'm real curious about what's going on with these machines. It may take a little time to figure it out but I'll sort out an update when I do.

Sorry to barge into another thread like this but do you think while you have Logic up on the MBP you can take a look at the Virta issue with left output only? Thanks.

@geremy, I haven't made time to look at that because I'm working full time on this more severe issue that is affecting a lot of people. Meanwhile I bet we can find you a good workaround but let's discuss it in the other thread, OK?

I've spent most of today running tests with Aalto on the MPB 13 and squinting at the results. Here are some observations.

There's no smoking gun. I thought maybe my code was creating a priority inversion or something else esoteric and bad on this hardware. But I'm not seeing that. Really, performance and behavior per core is a lot like my 15" MBP. With half the number of cores, glitches happen a lot more often.

Logic tends to glitch a lot more out of the gate than other hosts for two reasons. First, its default signal vector size is 128, which is fairly small. Second, it wants to redraw the screen more often than other DAWs, which is a big hit to the CPU. If I set Live's signal vector to 128, it behaves a lot like Logic on this machine.

All my plugins are based on a modular library internally that launches a lot of small DSP objects. It does seem like this particular architecture is doing worse on Mac OS Sierra for some reason, because the part of my software doing the dispatching of modules is itself taking up more time than it used to.

I could spend time tracking down exactly what changed, but regardless I have to make the code work well going forward, so I'm just going to focus on optimizing it. There's no quick fix but by combining some modules and getting rid of some to reduce the dispatch overhead, I should be able to make the plugins more efficient and update them soon.

Meanwhile, making the plugin window smaller and increasing the process buffer size to 256 or 512 should reduce glitches on Logic for users with 13" MacBook Pros.

seems like i'm having the same issue so joining in, can help test if needed or provide feedback..

el cap 10.11.2. 13" retina early 2015 mbp. 3.1ghz i7, 16bg. live 9.7.1 64bit.
if i just load live with one channel, and load kaivo, kaivo default preset, 8 voices.
idles around 60%, and cpu spikes while audio glitches out if i play lots of notes. (44100 with 2048 samples and 0 latency correction)

on my mid 2012 mb air, 2ghz core i7, 8gb ram, osx 10.12, i can do the same thing and the cpu idles at 50% never exceeds 60%.

That is unfortunate news. It is really sad when a flexible and simple architecture turns out to have just this one major flaw and it forces a rewrite into something less ideal.

Also, did you try Kaivo? It is worse and I wonder wether it's just because of higher complexity of the algorithms (when comparing to Aalto).

Kaivo takes up more CPU because of its DSP algorithms that are really intense. This is more expected. So I'm focusing on Aalto which should be having no problems on these computers.

while the problem happens in live, if i run virta in reaper it uses just 5-10% of cpu, au and vsti.

hi randy
thanks a lot for all your effort.... whats the actual situation ? any news since mid january ?
tschakka, you can do it ;)))


Working on it here. There's no one big thing to fix, so I'm fixing 100 little things. I'll post a new beta soon.