Fabfilter Pro-L (64) - Using 4x Oversampling

You're doubling the memory requirements and doubling the CPU load. Using the 64-bit engine also doubles the memory requirements.

Try disabling the 64-bit engine except when exporting, and raising your buffers. There is no real need to turn on 4x oversampling except during the final export, when large latencies are not an issue.

When you compress with a fast attack and release, as with a master limiter on an aggressive setting, you distort the waveform and thereby introduce harmonics. Some of those harmonics are going to be higher than the Nyquist frequency and will therefore cause aliasing. Oversampling at 4x raises the Nyquist frequency by a factor of 4, reducing the undesirable side effects of harmonic distortion. That's it in a nutshell.

I use Pro-L mostly for mastering or the odd track using 4x realtime but it's never crashed. Just a few things to mention:

What are your computer specs? are you running a dedicated daw- other programs running in the background?

What other plugs are using in combination with Pro-L ? Try disabling them one by one, see if problem persists.

I use Pro-L mostly for mastering or the odd track using 4x realtime but it's never crashed. Just a few things to mention: What are your computer specs? are you running a dedicated daw- other programs running in the background? What other plugs are using in combination with Pro-L ? Try disabling them one by one, see if problem persists.


Well, got a quad core 4x 2.5 GHz, 8 gb ram and only running Sonar with a new project file and only 2 vsts (Vengeance Metrum and Dune) in it. This should be more than enough processing power... i even kill network connection and antivir before loading up Sonar (task manager says before starting Sonar: 2% cpu usage).

Do you mean a VSTi loaded & playing midi?  that could be your conflict right there & I'd check that. Again I've never had a problem running multiple instances of Pro-L 4x with many audio tracks or vst's/ VSTi's.