Why are my CPU and GPU being utilized in a weird way?

[AladeenWasabi]

Hello! 
When I play a YouTube video on 4k, my avg. CPU utilization is around 35% and GPU utilization around 33%. When I switch the video quality to 8k, the CPU utilization is 99-100% and GPU utilization drops to 10% or often lower. Why does this happen? How can improve my laptop's performance? I currently have 4gb RAM, Core i3 @ 2.5 GHz Kaby Lake, Intel HD Graphics 620. The only demanding application I use is Photoshop. 

[WAWood]

@AladeenWasabi 

When you switch from 4K to 8K, you are switching between different source files of different resolutions and sizes.  The 8K version is a LOT bigger than the 4K version.  So, to maintain the same frame rate, a LOT more data has to be transferred in the same timeframe -- and that increases the load on the CPU to manage that data transfer.

And no, as long as you insist on streaming this resolution, you can not improve on this.