The Intel Core i5-8300H is a fast processor for laptops with four cores based on the Coffee Lake architecture and was announced early 2018. The processor clocks at between 2.3 and 4 GHz (3.9 with 4 cores) and can execute up to eight threads simultaneously thanks to Hyper-Threading. According to Intel, the CPU is manufactured in an improved 14nm (14nm++) process.
The Coffee Lake architecture is similar to Kaby Lake and differs only in the amount of cores (now six cores for the high end versions) and the improved 14nm process (14nm++ according to Intel).
The Intel Core i5-8300H should perform similar as the older Core i7-7820HQ (2.9 - 4 GHz). The faster Coffee Lake CPUs, like the Core i7-8750H offers two additional cores and is therefore up to 50% faster in multithreaded benchmarks. Still, the performance of the i5-8300H should be sufficient for even demanding applications and games.
The integrated Intel UHD Graphics 630 iGPU is supposed to offer a slightly higher performance as its clock rate has been increased by 50 MHz (rumored). The architecture is identical to that of the Intel HD Graphics 630. We do expect a performance improvement, but as a low-end solution it will probably only display current games smoothly at reduced details - if at all.
Intel specifies the TDP with 45 watts and therefore the i5 is only suited for big laptops with good cooling solutions. Using cTDP-down, the CPU can also be configured to 35 Watt resulting in a reduced performance.