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Max4life uses more CPU than MaxMSP


I noticed the following.

When running spat5.spat~ inside maxMSP. The cpu is around 30% on my MacBook pro (Windows Bootcamp)

However, When I try to load the Spat5.spat~ object inside a m4l device, my Ableton CPU meter skyrockets to 200+. Audio cracles, or a complete stop of audio happens after.

What causes the massive difference in performance between Max, and Max for Live?

My Ableton set is completely empty

Greetings, Marijn

Hi Marijn,

Max for Live always uses a signal vector size of 64 samples (as far as I know).
That can explain (partly) the major CPU increase.
Automation also might have a strong impact on CPU.


Hi T,

Thank you for your reply.

Is it possible to change the max for live IO vector size?

I have no automation, just an empty Ableton project. Even when I have no sound going trough spat5.spat~, the CPU meter is at 50 / 60 %. When I Try do do anything with spat, I get numbers over 200. Changing my buffersize, or driver settings in Ableton does not have any effect.


It’s possible to change the IO vector size, in Ableton’s preference page.
But it’s not possible to change the signal vector size (i.e. rendering block size), which is hard-coded to 64.

What is your OS/hardware ? Running Windows via Bootcamp on a MacbookPro ?
Can you maybe give it a try on another computer ?

Things run fine on my (macOS) machines with Live 10.
CPU load is similar to what you would have in Max with signal vector size = 64.

There are bunch of other M4L users on this forum. Maybe they could report their own experience ?


Hi T, Thank you for your reply

I have a Macbook pro 2020, 16 inch model. I7 processor, 16gb ram.

When I run spat in Ableton m4l on MacOS, everything is fine. (around 20% cpu used, and is stable)

I also have Windows 10 installed via bootcamp. Running m4l + spat on my bootcamp results in very high, and fluctuating numbers. The Cpu usage wil swing around from 30 to 200+. Ableton often freezes. I checked the Windows Taskmanager, and it states only 2% CPU is actually used. This indicates to me that it is only a problem within Ableton or max. The rest of my computer will run fine with no lag.

So huge difference between running spat on Windows OS, vs MacOS on the same PC.

Greetings, Marijn

Hi T,

I have concluded that it is a hardware issue, rather than an issue with spat. I tested it out on a very fast windows machine, and all my problems where gone.

Thanks a lot for the report. That’s good to know.