I already explained that, twice.It's strange that the processors are at very similar speeds 9 years later.
Another factor to know, is Intel for over 5 years was incredibly stagnant due to severe lack of competition until 2018. From the 6th gen to the 10th gen used the SAME Skylake architecture for all cores, just mildly tweaked year after year.
Your current runs at 45W, the 6300U runs at 15W. 30 watt difference, lower core clocks, and yet still manages to stay faster. On the desktop side, an i5 6500 isn't much faster than a i5 2500k. Differences in efficiency, that's about it explained in quote one. Let's also not forget, Userbench is not a good comparison.The 6300U on the other hand says "5%" because it's a low power variant, that's what the U is. It's a 15W chip and lower clock speeds. So not only is it technically still faster, but it's doing it at 20W less power draw.
Faster and more RAM. You have DDR3, the 840 G3 uses DDR4. It will also have a faster SSD than what you can put into your current machine.Also did you mean *faster* RAM or just more RAM?