Is it me or does 2.1.0 use more CPU than 2.0.0 do? 
Playing the same song on both versions I notice a CPU-usage increase with about 4%. I know, not much, but couldn’t it make a big difference in a song with lots of channels and effect (and whatnot)?
Just worried that some day I’ll reach my CPU limit with the new version while it works fine with the old one. 
In overall, Renoise 2.1 will be as fast as 2.0. Maybe sometimes even a bit faster. And don’t worry. New versions do not necessary mean more overhead. In contrary. I’m constantly doing small performance improvements here and there, as soon as I stumble upon them.
Also when testing something like this: Make sure you’ve got exactly the same Audio settings (driver, samplerate, latency, PDC settings, multicore settings), becaues all those have an influence on audio performance. Every new Renoise version you install will have its unique preferences, so if you change something in 2.1 this won’t affect 2.0.
If you still worry about this, and you think its worth that, send me the file with the 4% more load and I will take a look at this here…
Ok, so I checked all the setting in both versions and tried the same song again… and now they’re a the same CPU-usage. 
I guess it was just a temporary thing before… weird. Anyway, thanks for helping. 
just for fun,…
running rns 2.0 on VIA C7M 1,7 GHz and Intel atom 270 1,7 GHz gives not bad performance.
VIA is slower but Atom is very usefull.
Unfortunatelly none of music sw can use atom’s virtual muticore, does anybody in Renoise development team know why ?
Also, none of 2.0 demo songs can play on C7M and Atom, but older “digging for gold” plays fine on atom.
2.0 demos are extremely cpu consuming. But for composing on road is Atom ok 
By using small machines I’ve discovered that lot of cpu time consumes equalizer effect. Most of rns effects works like nothing to cpu.
and btw rns 2.0 is smoother and better in cpu consuming then ableton live 8…
I’ve noticed on my old G5 that several files that I created in 2.0.0 (that had heavy use of plug-ins AudioUnits/VST, etc.) cannot be played back from beginning to end without extreme stuttering and audio break ups while running them using version 2.1.0.
Even the Beatslaughter Vs. Tenda demo file stutters in 2.1.0 on my computer where the same file always played without a hitch in 2.0.0.
This is not totally unexpected. Although I am still able to squeeze a lot of music out of my old Mac G5 (8GB RAM - RME 9632 sound card | OS X 10.4.11), I understand that technology must march on.
I keep this old G5 in service for using certain pro audio plug-ins and programs that either aren’t made or supported any longer that I love, or for those programs that still don’t function well on an Intel (non- PowerPC) based Mac running Leopard.
Still, one of Renoise’s ‘charms’ is its ability to run well on older systems. To that end, the older versions of Renoise offer many choices for the ‘vintage’ computer user (like me) which can allow someone to still enjoy Renoise despite the use of an elderly system.
While I’ll keep trying to use 2.1.0 - if it’s too CPU intensive for my old G5, I’ll have to switch back to 2.0.0 and hope I won’t be missing out on too many cool features for the time being…
Slewing has been disabled and the processor set to maximum on this machine since 2005. (Energy Saver pref. pane) It needs all the help it can get.
However, after running additional optimization utilities (cache, delete log files) on my system just now, I am getting better performance. Beatslaughter demo plays much more smoothly now. Thanks.
I’m certainly enjoying many of the new features in 2.1.0 - overall, an amazing program at any version.
Another thing that can have a very deep impact on the overall CPU usages is the audio latency - beside of course the sample rate. Using 1ms can lead to a doubled CPU usage compared to 10 ms for example. How slower/faster this is exactly depends on various thing, but in overall, higher latencies are always lower on CPU.
So probably you are using a different latency or sample rate with 2.1?
It seems that this also applies to AMD CPUs using Cool’n’Quiet.
I get more crackles having my CPU running at “low energy mode”, this gets even worse when PDC is enabled in Renoise.
Switching to “desktop energie profile” makes everything work finest.
Update the Wiki? 
That and using a vacuumcleaner to suck out the cool-ribbons before hot summer strikes hard as the usual reminder…
(computers that turn slower, or start to hang often)