I am a user of Nuendo 10.3. It works perfectly for me. I do think it’s performance is variable and dependent on the systems it’s running on. I was having the same experience as you two months ago until I changed my PC. I currently have an HP Desktop, 32 GB RAM, about 3.5ghz speed, 2 Terabytes hard drive (1 terabyte Solid State as system drive and the other as storage), Focusrite 6i6 soundcard, and Steinberg USB Driver too. Since I changed my system, Nuendo has not crashed one bit, nor has its CPU meter spiked ever since.
Given the perfect conditions, Nuendo will crank up on you so you probably need to do the following:
(1) Check your audio input levels when recording your tracks. If they are too hot, you can push your levels too much and you get clipping and then Nuendo will respond in unpredictable ways…might crash, freeze or do some crazy things
(2) Check the volume of your clips…make sure before you process them (when they are raw) their volume hits your meters at -18db, cos once you start slapping plugins on those channels/tracks, your volume will hit like -6db and that’s very close to clipping.
(3) Check the volume knob on your soundcard…if they are too hot, you are feeding Nuendo with too much volume and it might clip.
(4) Check the space on your hard drive and ensure you have at least 300 GB free on your system drive
(5) Do not save your working files/session files on the system drive…do so on your extra drive.
(6) Archive all your old files you don’t need currently and put them on an external hard drive and free up memory for Nuendo
(7) Check the plugins you process with…also scan your system for viruses and malware as they can contribute to system malfunctions. It might not be Nuendo, but an inhibiting malware.
(8) Don’t run Nuendo at the same time with another DAW…if you have different DAWs…also some other CPU intensive applications should be close. If possible don’t surf the internet at the same time as you are running Nuendo except absolutely necessary, as web resources consume CPU unless you have big CPU.
To sum up, the problem is definitely not Nuendo, as all of us here downloaded from the same source…its the same software. I’m not experiencing any issues, but I was while using my former system. Once I upgraded to a better system, problem disappeared. So now I know what it was. I hope this helps you.