First off, I run a PC and I can use Cubase while playing audio from youtube just fine!
I will say right now that I think your hardware should be plenty, as long as you don’t have tons of VST loaded in Cubase. (No huge and complex plugins, etc.)
I sometimes play guitar routed into cubase with some insert effects from a few plugins, and I can play along with audio from a video from youtube or a video clip on my computer.
(I am not great at guitar, but I use the videos to try and learn.)
So I know that it’s possible for cubase and youtube to work together on windows like that.
I will list a few different possible causes of the delay, how to diagnose them, and a possible software solution.
I don’t think you will need to change hardware, but it’s possible, so I will list alternative hardware solutions as well.
1) Lack of CPU resources
If the CPU gets overloaded, it may ‘stall’ the less important task. Windows might be deciding that youtube is not as important, and hence, the video hardly gets any CPU time.
How to diagnose:
Go into task manager and check the CPU usage. If CPU usage is sitting above 50% all the time, this may be the cause. Your processor (the i3-6100 from what you said) is dual core with hyper threading. This means that any time CPU usage is over 50% some things might start to get slowed down. If CPU usage is usually under 50% when this is happening, it’s almost surely not the case.
Make sure there’s no other pesky software running that’s taking up your CPU time. Also, try to only keep one tab open at a time in your browser. My brother keeps dozens of tabs open, and all of the adds keep taking up his CPU!
Alternatively, upgrading the processor to an i5 or i7 would improve performance considerably.
2) Poor performance of graphics hardware
The i3-6100 has a built in GPU, and I believe a media decoder unit as well.
CPU based media decoders are normally improvements, but possibly might give poor performance while doing something else at the same time.
How to diagnose:
Does the problem happen only when cubase is running, or does it happen if you run something of similar load to cubase? A (simple) game would be a close match to cubase, I think. If the problem also happens when running the game, then this could be the cause.
You would need to the web-browser or the youtube video player to not use the media accelerator in the CPU.
It would be a matter of disabling “h.264 hardware acceleration” in the video player. Not sure exactly how, though, unfortunately. The settings for these things are never where I expect them to be. Might be a right click on the video? It used to be at least.
Alternatively, getting a graphics card may help. Even a very cheap one should do wonders for video performance.
3) Running out of RAM
If you run out of RAM, your system will start using virtual memory on your disk. This will cause intense slowdowns for anything that needs to load into memory. It would seem to fit that longer videos may require more memory, so this could explain why it only happens on long videos.
How to diagnose:
Open task manager and check the memory usage when this happens. You are looking for the total “physical” memory usage. If it’s maxed out, then you’ve got a problem!
Close any application you don’t need open, and try to keep VST usage to only the minimum you need.
Alternatively, you could get additional RAM for your computer. Based on the specs you posted, your board should have two slots, and you’ve only got one stick now. Getting another 8GB of the same memory would give you 16Gb total. That would give you as much as I have, and I rarely ever run out of ram!
Unless I try to use some East/Wests VST plugins…
4) Audio interface / ASIO / Other software issues
I don’t have a concrete way to diagnose or solve this, but there are many things that can be played around with.
There’s a lot of questions you could ask yourself to help narrow things down.
Do you have windows using the audio interface, or your built-in sound card? What happens if these settings are changed?
What happens if cubase is set to use the Generic ASIO Driver, instead of the audio interface?
Does the issue go away when not using the audio interface?
Does the problem happen as soon as cubase is opened, or only when certain effects are loaded?
Alternatively, trying a different audio interface may help. I use a Saffire Pro-14, and a Line6 UX2. They both work, though the Pro-14 has much better latency in general, and way better pre-amps. I mostly got the Line6 for the guitar effects.
There’s of course, all kinds of other random things it could be, but these are the ones I know how to fix.
Also, following Procks suggestion to disable the Steinberg Hub may be worth a try, too, since this happened to me in a previous version.
Good luck! (For the record, I am a PC person. )