Optimizing Reason performance on a Mac for a CPU-hungry song

June 05, 2007

I like Propellerheads Reason. It’s a great piece of software for messing around with digital music.

But sometimes you come across someone else’s song that not even the fastest MacBook Pro can handle :) someone has put so many samples and tracks and synths into one production that the poor computer pukes under the load, you see your CPU going through the roof and the thing just doesn’t play nicely.

But there are two little things you can do to finetune things. They are both in the Audio preferences of Reason.

Increased buffer size

The first thing you want to do is to increase buffer size. This makes the app a bit less responsive, but reduces CPU load as the audio is precalculated in larger chunks. So if things start to distort due to too high CPU usage, this is the first thing to try – slide the slider to the right, increasing the buffer size.

Reduced sample rate

If the above doesn’t help, here’s another tip I found in Reason’s manual. You can reduce the sample rate, meaning that the song is calculated and played with a lower “resolution”. This makes it sound worse as higher frequencies are lost, but you can still get a quick idea of the song. For full quality, you can always export to WAV.

But here’s the thing: the Mac internal audio (if you’re using headphones plugged into the Mac’s “audio out” port) has 44.1 kHz as its minimum sample rate, so you can’t go below that and you can’t use the trick. However, turns out that on my USB headset, you can set lower sample rates as seen on this picture. So this is what I can use to quickly get an “overview” of a song if it’s too CPU-intensive.