Renoise and Conserving CPU on Old Machines

For about a year, I was limited to using Renoise on a measly Fujitsu Lifebook Series B circa 2000. In other words, a notebook designed for pure business use (think Microsoft Office only); an 8MB video card, 256MB of RAM under Windows 2000 powered by a 700Mhz Pentium III processor. If you look at the official 'required' specs for Renoise, you'd see that I fall short of this. However, I was able to make music without much restriction. But first, you must let go of everything you know...

Minimize VSTIs

Now don't misinterpret this instruction as "DON'T use VSTIs". There are decent ones that don't use a lot of CPU power and are quite nice; Synth1 comes to mind. Preferably, though, you don't want to corner yourself into having to replace a VSTI with a sample late in a song, so just assume you won't use VSTIs from the beginning. When it comes down to it, most of the time, the only parameters you'll use during a song is a filter. Render out some notes or even a riff or two instead of wasting CPU power on a VSTI that's not sounding much different from pattern to pattern anyway. You'll find out later that you have slightly 'more' control of the sound this way by way of the 09xx command. Avoid using CPU hogs 'live' at all costs (e.g. Crystal). Sample them ONLY!

Minimize Polyphony

After eliminating unneeded VSTs, don't start running your processor into the ground with a plethora of instruments with long trailing times and and filter envelopes, because you'll have just defeated the purpose of clearing out the VSTIs to begin with. Whenever possible, eliminate the filter envelopes as well. A simple sample with the filter in the track works just as good in many cases and allows you to use it across more sounds. Reducing polyphony also goes for people that waste 15 tracks for drums - 2 or 3 tracks with a good majority of sampled and looped sounds will do the same job. Plus you can 'glitch' them up a bit when they're sampled by using the pattern effect codes.

Minimize Effects

On my personal tunes, I always make sure that I'm able to run my favorite multi-band compressor and brick-wall limiter on the master track. If I can't, I delete other effects. Try to find an effect or two you just can't live without, even if it differs from song to song, and treat those as part of the song. Don't get to crazy and start thinking that your chain of 50 effects is necessary to the song, though. When you start running out of CPU start thinking to yourself about other ways to do the delay (multiple notes on a track, oldskool tracking style? You bet!). Is the filter on this 'backing' track really noticeable behind all of the other sounds? If not, delete it. Another way you can do this is make use of the sends tracks. Don't use a different style reverb for every track: just make one reverb and set the send slider to it differently for each track. You can even switch on and off things like Flangers by way of sends meta devices by keeping the source and setting the sends accordingly. It takes more work to decide what to do in each song and each situation, but generally in my experience, you shouldn't need more than 2 delays, a reverb, 3-4 filters and 1 or 2 gratuitous effects like Lo-Fi and Distortions per song when you get to the core of the music you're working on. On a side note, working like this will sometimes help you view writing music differently, relying less on VST wizardry and more on tracking itself.

Minimize Sample Rates

You can get a speed boost here and there by putting less demand on the RAM. If you're not an audiophile and don't mind 16bit samples, then export your rendered samples and convert them into 16 bit. Less sample data in the RAM = more room for your wisely chosen effects to process data.

Examples?

Well, here's one... Maybe it's not everyone's style of music, but, it runs on the aforementioned LifeBook just fine, maxing out at about 30% CPU usage. Yes, even the end patterns. NOTE: Example uses Karma FX Filter, BuzzRoom GranComp3 and MDA Dynamics (in their Effect Pack).

Less is More

All in all, conserving CPU is a hard topic to explain, but once you get in the swing of things, you'll notice that you'll use Renoise more like a "powerful tracker" with a few chosen effects and synths - rather than Renoise as a pure VST host, which is the quickest way to get that dreaded 'Maxed-Out CPU' message and skippy audio. "Render Selection to Wav" is definitely the most used feature of Renoise and the most versatile. If you ignore it, you're headed to a low CPU ceiling headache.