The game is not going to the maximum possible. The graphics load is 50% and the CPU 55%
Any way to increase performance?
HotS will use only about 2 threads heavilly. The i7-8700K is a 12 thread part (6 cores * 2 hyper threading). Hence the total CPU usage while playing should only be ~17% or less. If it is reporting 55% total CPU usage then some background application is using a lot of your CPU time and likely causing a resource contention with HotS.
The i7-8700K also comes with Intel® UHD Graphics 630 integrated graphics. You do not want to use these to game on as they are painfully slow compared with your RTX 2080 and will further cause resource contention with the CPU in the form of memory bandwidth. Make sure your display is plugged into your RTX 2080 PCI-E card and not your motherboard. If the display is plugged into the motherboard then games will try to use the weak/slow Intel integrated graphics instead of the powerful NVidia RTX 2080.
HotS is not a high frame rate game so you should be expecting frame rates in the order of 60 (maybe slightly less, this would be an extreme 5v5 team battle on Blackheart Bay) to 200 FPS (countdown at start of a match) depending on the content being displayed.
I have IGP desactivated.
Even if I leave running hots alone, there is no more than 60% graphical use. And a 8700k at 5Ghz with 32Gb at 4140Mhz won’t make a bottleneck. I also have all solid disks optimized.
A friend of mine has the same team practically and the same thing happens to him.
Problems of being an old game engine?
if you activate dsr 4x the use of gpu is 100%, the cpu is the same and goes to exactly the same fps.
that is, the game works equal to 1080p than 4k
What FPS are you actually getting?
Your processor and GPU should be getting anywhere from 100 to 200 FPS. This is what my Ryzen 9 3900X is getting with a GTX 760 (old, slow, mostly likely the bottleneck) and your CPU @5 GHz with a fast modern RTX 2080 should have similar HotS performance. The 8700k uses as good as the same core designs to the I9 9900K which is still faster single thread than the Ryzen 9 3900X when running at 5 GHz.
If you are overclocking it is possible your overclock is unstable. Slightly unstable overclocks will not cause a crash but will massively degrade performance. This is especially the case with memory overclocks, which I guess you are using seeing how you have 4140 MHz DDR4. This is especially the case with memory on the RTX cards. Try reverting everything to stock and checking performance. Overclocks are only faster if one proves they are faster with a specific workload, otherwise they can actually be slower.