I only see about a 1.5% CPU diff between 2.4.1 and 2.5.2 with same patch, so yes, much better, but not yet same, if no 2.5.x features usedā¦
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Sounds good! 1.5% is probably in what I would call āmeasurement noiseā and those numbers tend to bounce up and down a bit. Sounds roughly like āunchangedā to me and I think thatās the important bit. Of course, you could try and make a large and taxing patch, then measure on both versions, and see if you can make the difference consistently larger than that. If not Iād say job done.
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for those of us (me) who is still on 2.4.1, should we still wait to upgrade? i cant afford any glitches right now!!
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There are ways to keep two versions of Rack on your machine (previously posted on this forum, but I donāt have the reference for you), so you can keep your working setup and also experiment with the latest (now 2.5.2).
I canāt afford a drop of performance now, I am waiting for good news on this community. 
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The CPU consumption has changed positively. I also had big problems with V2.51. After update V2.52, I have the impression that it behaves like V2.41. Good luck.
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While using 2.5.2 for the first time yesterday, I noticed that the only place I experienced crackling where I had not previously, was while browsing the library.
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For me 2.5.2 has been on par with 2.4.1, soā¦ happy times.
(Thanks devs! 
)
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whats your system
Win7
how did you get back to 2.4.1 ? I am having the same issue and with 2.5.1 and the patch is unusable I have tried everything I can to think to fix it even removing modules that seem to use more CPU and still sitting at 150% with crackling and constant audio problems.
Before you go back have you tried 2.5.2 ?
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I downloaded 2.5.2 on my other laptop to try it because I canāt risk losing the patch (its for an assignment) it was the same result. What I have had to do is get rid of nysthi simpliciter in the patch and now its spiking at around 89% which is useable, kind of. strange because iāve had way bigger patches before that have never spiked this high.
Hi and welcome to the forum! Could you send the two patch files, with and without Simpliciter, as well as your log.txt file (found in your Rack user folder) to us at VCV Support so we can look at whatās going on?
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Glad VCV Support is on it! In the meantime, @sophiekilworth, if you want to get to 2.4.1 the binaries are available from the dev blog: it says āpre-releaseā but the files are final . If that causes trouble with paths, etc. you can build 2.4.1 using the relevant Github target and instructions available here, which will give you an isolated install and is a good experience if you ever want to get into Rack development. Good luck with the troubleshooting and the assignment!
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Iām still getting approximately 70% CPU usage in 2.5.2 Pro with an empty patch on an i9-12900KF.
How many threads configured?
Yikes! Iād definitely contact Support with details. Did 2.4.1 work fine? Does 2.5.1 have the same problem?
Iām starting to wonder if this issue, at least on Windows, which Iām most familiar with, is caused by an underwhelming Power Plan. If I run my laptop (4 x i7-8565U) in the default Battery plan (on battery), pretty much anything CPU intensive ends up crackling the audio. If I run my laptop with AC, that Power Plan seems to work just fine with VCV on 1 Thread. Most likely because in AC mode the CPU gets overclocked.
Then there is the approach taken by FL Studio. When launched on a laptop it flips automatically to maximum System resourcesā¦
BTW, if this might help, I experienced this also when I run Pure Data with a weak Power Planā¦
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Iāve definitely had trouble in the past with Windows laptop power management. On one machine I even needed to go BIOS diving and turn off all sorts of HW-level efficiency features to avoid crackling under load at any buffer size!
Maybe Windows issues are creating false positives for 2.5.2. I hope so, since the known perf issue from 2.5.1 (regarding port-based cable summing) seemed to be definitively fixedā¦
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