Just because you are now running a more recent kernel does not mean that the kernel would be the culprit. As the matter of fact, you’re running an LTS kernel, which is about as stable as it comes.
The kernel was also not the only thing that got updated, and as the matter of fact, chromium has also been updated recently — more than once even, because we fast-track that one for security reasons.
This is commonly due to a process hogging the processor.
It could be that the process is stuck.
It could be that you’re running out of RAM and that the system is starting to page out the memory contents to the swap device.
It could be a graphics driver issue — you mention watching YouTube videos.
Either way, without further information, there is nothing more we can tell you. So please read the folowing two posts…
