@ffx well I just googled “what is spectre” and then got lost on the internet 
Found a tool called InSpectre that checks and can disable “Spectre” and “Meltdown”. The tool told me that my system is not Spectre protected.
Right now I’m looking for something that is not up to date.
Feel free to keep sending me suggestions!
Thanks
Just to keep you in touch with what I am doing:
-Running defrag
-Running CCleaner
-Uninstalling unused applications
-Making room on my C drive (even if there is already 100 Go of free space)
Things are getting weirder…
I tried to plug my old pc (win7) and everything worked great in Renoise(2.8 on that computer)!
Old computer:
AMD Phenom 3 Core 2.3GHz, 4Go RAM (desktop)
A 10 notes chord made my CPU usage go to 40% without cracking sounds with the Nexus VST and the Grandpiano preset. Asio4all and berhinger uca202. 2.9 millisec latency.
Latest computer:
Intel Celeron 4 Core 2.16GHz, 8Go RAM (laptop)
A 5 notes chord made my CPU usage go to 80% and I hear cracking sound. Same VST same preset same asio4all same soundcard same latency.
Thoughts?
Intel Celeron
I suspect it’s your CPU. I’m assuming your laptop is using a N28xx series processor. The Celeron shares it’s L2 cache between cores and your model lacks an L3 cache all together. The Phenom, on the other hand, has a individual L2 cache per core and a large L3 cache. In essence, there is not enough data being sent to the 4 cores of the Celeron via the caches to be processed in real time. On a laptop you have Intel integrated video that further loads the CPU as video memory is shared with data memory so some CPU cycles are dedicated to video updating.
When the Celeron L2 starts to choke, it falls back on accessing slower system RAM. The CPU loading you see increased is due to more CPU cycles needed to load the caches. That’s why you hear the crackling. If you were doing video processing, you would see “artifacts” on screen and much slower processing times.
Intel Celeron processors are best suited for desktop or laptops running low CPU tasks such as word processing apps, web browsers and so on. For audio work, I’d suggest at least an i5 multicore or comparable AMD CPU.
Cheers.
Thanks for the informations @The_Traveler.
I am aware that this computer is not really good for music production. It was a cheap laptop that I bought with all my money for a gig in Germany.
One day I’ll have enough money to buy a better one.
Anyway, it doesn’t change the fact that this computer was running Renoise WAY more smoothly like a month ago!
I haven’t made any major changes on my configuration or installed a lot of applications lately.
This drop in performances is still a mystery for me.
Still looking online for clues. At this point I start to think it might be a physical problem.
I wouldn’t discount a Windows update having a negative impact. Intel and others released patches to fix the Meltdown and Spectre CPU exploits to directly access system memory via the L1/2/3 caches. The patches have varying performance hits depending on how frequently an application accesses memory. Audio and video processing would see noticeable decreases in performance.
As your running Win10, the MS patch was pushed to you, and I think it fits the time frame you mention.
Conner_Bw has a point. You might check your power management settings and make sure they haven’t changed. I’ve seen all kinds of weird things change on my wife’s Win10 desktop after an update. Who knows? 
Cheers.
That is very interesting @The_Traveler and @Conner_Bw
That is also a lot of things I have never heard about and need to investigate (with my poor googling skills 
).
I will have time later today to do researches and tests and will keep you guys in touch.
Thank you for helping me out! Really appreciated
BIG IMPROVEMENTS!
While trying to follow @Conner_Bw link, I was first horrified to find out there were no more power options in my parameter window!
Turns out it was at another place now. You have to click on the battery logo to access them.
And there I realized that windows has changed my power saving parameter to “balanced” without asking me!
Switched it to “optimal” and I already saw a very significant change!
I’ll do some more test before putting this thread on [SOLVED] but I think you guys just solved my problem!
More soon …
EDIT:
YOU GUYS DID IT! 
All my tracks are working again and I am able to play live VST without any cracking sounds (as long as I do not push too many keys at the same time).
I want to say thank you to the awesome Renoise community and especially to @The_Traveler, @Conner_Bw, @ffx and@dblue.
Thank you for your patience and kindness! You are awesome <3
And now back to music
Cheers!
Excellent! Happy to hear you were able to solve the problem.
Cheers.
Hello everyone, sorry to do that but I’m joining this thread 'cause I’ve had exactly the same problem since last week but I have an AMD FX 8350 (8 cores 4GHz) and I’m on win7, 16 Go Ram.
I’ve tried everything said on this thread (meaning format and reinstall windows, increasing the buffer, disabling CPU throttling, checked withInSpectre : says it’s metldown protected but can’t do anything about it…
and I checked my ram with memtest and my hard drives with crystaldiskinfo and there’s no problem with that)
And I checked for all my equipment and system updates…
But I’m not as lucky as PPLo…
The only thing I can see now is my blackbird onyx firewire is dead… but I don’t really know how all of this works so I’m left without a clue. Could it be the firewire cable? or the IEEE 1394 card?
I tried to put an old M-audio delta 44 and it was the same…
And I tried on both 32bit and 64bit version of Renoise. I have the same problem in cubase (both 64bit and 32 bit) with the asio load being 100%…
But I tried to make a short edit in Adobe Premiere and I had no problem.
Do you have the same issue if you configure Renoise on direct sound or is it only on asio?
Maybe try to disconnect your FireWire device, then reboot and test it with the PCI audio device. Could be indeed a faulty FireWire, and I guess you have to reboot, if the driver hangs. Or even temporarily remove the FireWire adapter,
Hi, yes, it’s even worse with directsound, and I tried asio4all too.
I did disconnect it and deleted the driver and installed the M-audio PCI instead too.
Thanks guys, I’m really desperate.
Okay, I tried to boost cache memory usingfsutil behavior set memoryusage 2 command.
Seems to be way better. I guess it’s clue a the problem is with cache memory.
But still, it seems weird this happens overnight…
Good thing you solved your problem!
Thanks man! It seems I got excited quickly, it’s better to the same 10 minutes after…
Oh, and I just heard about a DPC latency checker. But everything seems fine, I’m so lost.
Here’s the link, it could be useful.
I discovered that using 32bit Vst’s with Jbridge in a 64bit Daw decreases the Cpu usage quite much!
I also found that tool that is pretty cool : Latencymoon if anyone is having trouble.
So it seems it has something to do with a Windows update concerning Direct X dxgkrnl.sys… but I don’t find much on this…