I am surprised you were able to get it to work at all because :
1. Go Pro footage is highly compressed and difficult to edit natively without a very beefy machine. Many users transcode that footage to the free cineform " edit friendly" codec supplied for free with the free Go Pro Studio application. Your new "Kaby Lake" CPU does NOT have 4 cores/8 threads like most i7 CPUs found in gaming laptops used for video editing,but, rather it has 2 cores with 4 threads. Somehow, ( probably because of the "turbo" to 3.5Ghz), it manages to at least encode the difficult 4K to 1080p.
16 GB is marginal by today's standards....especially when working with 4K.......32 is much better and 8GB is surely a GIMP to the machine with 4K and 1080p, reducing performance. My own 2 year old laptop has 24GB system memory and I've seen it use 20GB while editing a complex 1080p timeline. Newest versions of PPro use more system memory than past versions to improve performance, especially with 4K.
2. Any normally CUDA accelerated effects, scaling, or, transitions will NOT be accelerated when using an AMD GPU. An NVidia GPU would accelerate these processes by a factor of TEN TIMES to dramatically reduce export times. Only NVidia GPUs work with the "Mercury Playback Engine" to provide CUDA acceleration.
Your conversion from 4K to 1080p is a scaling operation that the AMD GPU will not accelerate like NVidia would.
3. 4K footage requires at least 4GB of video memory on the GPU to provide enough memory for "frame buffering" and other things. You do at least have that, so you won't have a "bottleneck" there.
4. The use of only one drive withPPro is not advised, unless you are using a brand new PCI NVMe SSD which is connected to Gen. 3 4x PCI lanes. Spinning mechanical hard drives will also diminish performance and are not advised to use in active editing or exporting. They CAN be used as backup,or, archive drives. In your case, it would be better to add a second SSD, if your machine allows it. Only OS, programs and Windows page file would go on your " boot drive". You CAN place the " media cache" and "cache files" in their default position on the boot drive without any penalty to performance, and that makes it easier to erase them when a project is complete. All other files should go on a second SSD for best performance., ( i.e. exports,previews, project files, and all media ).
If you dont have a second drive bay, you can use a high speed external port for that second drive. However, you would have to make sure that the speed of that external device is plenty adequate...meaning that it should be running at least at 400MB/sec read and write, like a Samsung T3 drive would do connected to a standard USB3 port. Your machine appears to only have USB 3 and not any of the newer,faster external ports. That Samsung T3, ( or the older T1 ), uses something called " USAP" to enable that faster speed over the USB 3 connection to reach over 400MB/sec. transfer rate. I have one, it works great.
In the future, if you are limited to a laptop, remember that any laptop used for editing must be plugged in to AC as it will automatically " throttle" while on battery no matter what power settings you have made It is better to have at least 4 cores and 8 threads than your current CPU and also better to have an NVidia GPU.
Thank you kindly for your response. I understand that the machine (laptop) is not made for video encoding and i am an amateur so i don't ask to much. The fact that i wanted to understand is why i have 10x gain when i just add 8 GB of memory and make it dual channel. I had before a Broadwell i5 CPU (2 core also) and the encoding would take 2 hours. When i first started with the new laptop, 13 hours, it was staggering. After i added the ram and ran the same encoding settings it sped up 10x, and thats incredible!
...you may have not assigned the memory correctly under "settings" in PPro. Ideally, I have read that a minimum of 3GB of memory per "thread" is needed by PPro...which in your case would be 12GB assigned to PPro and 4GB assigned for "other uses"
Also, Windows "power settings" must always be set to "maximum performance", as the DEFAULT settings may throttle the laptop even when plugged in. I experienced this with a new laptop once....of course, any laptop MUST be plugged in while editing or exporting or the machine will "throttle" no matter what the power setttings are.
The single stick of memory was GIMPING your machine...it obviously was easily maxxed out and thus became an overloaded "bottleneck". If it works "ok" for now, don't worry about it....its really not worth upgrading anything with the inferior CPU and GPU.
If you ever get serious in editing and MUST be limited to a laptop, look to the newer and faster gaming laptops which have :
1. i7 - 7700 Kaby Lake intel CPU 4 core/8 threads
2. minimum NVidia 1060 GPU w 6GB video memory...( 1070 much better )
3. 32 GB system memory
4 M.2 PCI Gen. 3 x 4 lanes slot for connecting a Samsung 960 Pro PCI NVMe SSD for absolute fastest speed, ( 3GB / sec read, 2GB sec write). With a 1TB version of this SSD, separate drives are no longer need...everything can just go on it.
5. minmum 17.3 inch 1080p display, preferrably IPS.....higher resolution not needed at this small size....pixel density is fine.
6. High speed external ports for connecting high speed external drives ,or, larger external monitors. ( I currently have TWO 1440p IPS monitors running at full resolution at 60fps on my laptop for a total of 3 screens with NO problem ! ).
Thank you for the great help!