CPU load stays high after freeze - SOLVED

Hi a question from a newbie :

I have a project which contains several plugins including an instance of Halion Sonic SE using 5 midi channels from a, previously dissolved, instrument midi track. The ASIO meter started to run high with audible glitches as it peaked in the red. This was not in itself an issue as I froze the VST instrument. After freezing the instrument the ASIO meter remained high at idle and on playback I continued to get audible glitches.
I saved the project, restarted cubase and reloaded the project, following which the meter showed 10% at idle, slightly higher on playback but with no audible glitches. I then unfroze the instrument and the high load and glitches returned (as I would expect) but on refreezing the high CPU load and glitches continued until I restarted Cubase again (this I did not expect).

Am I doing something wrong?

My system is a 2GHz Core Duo laptop with 4GB RAM on Vista 32 bit. The audio interface is M-Audio Profire2626 with the buffer set to 256 samples.

Thanks - Dave

If you don´t need low latencies go to 512 or 1024…

Thanks - increasing the buffer size improves the headroom before I run into problems but after more experimentation this morning I see the following :

If I run enough plug ins I run out of CPU headroom (as I would expect and confirmed by monitoring in task manager)
Once this happens the audio breaks up and playback slows (again as I would expect)

The part that I was not expecting was that from that point onward the CPU demand remains high, even if not actually playing and even when I freeze VST instruments. This remains the case until I restart cubase.
Once restarted the project plays back without a glitch even at low latency.

Note : Freezing and unfreezing tracks / instruments before I run out of headroom seems to behave the way I would expect.

So my question should have been - following CPU overload, is it normal to have to restart cubase 6 after freezing tracks in order to free up the CPU, or am I doing something wrong here?


Hi Dave,

Did you unload (one of the options in the freeze dialogue) the instrument when you froze it?


I think I was seeing this behaviour already in 5.5…Haven’t yet experienced it in C6 but current projects are fairly light.

If asio use is very high sometimes freezing quite a few heavy use plugs/instruments didn’t seem to help at all.
I could never work out when it would happen it was only on certain projects.

My solution was to export audio mixdowns & then remove the plugs manually (obviously making it more difficult to step back & make changes)

Hi ,
Yes I did use the option to unload the instrument when I froze it but the CPU load remained high (I used task manager and it showed that Cubase was still using most of the CPU time).

Look’s like I’ll have to put this down to one of those moments when you just have to reset and reload. Nothing is lost - the project can still be saved (although saving does take a while with the CPU maxed out!).

I will do some playing around and see if I can narrow it down further to a particular combination of plug ins alongside the Halion SE instrument.


Did you turn off EIST and HPET in your Bios?

with my machine it did miracles!!

Wow - now you’ve opened a can of worms :smiley:
These options are hidden in my (Phoenix) BIOS. Time for a bit of google research on how to unlock it …

Thanks again

Thanks to all who commented and especially to Submarin who pointed me at the answer.

My problem was indeed CPU Throttling which effectively was cutting my CPU in half as the load increased and the temperature rose - but way before it was actually required. I could not access the BIOS to turn off EIST (as this is hidden in the ACER BIOS) but a bit of searching turned up an extremely useful utlity called Throttlestop which enabled me to confirm the problem and address it in software.

A great result - thanks to all !