The score you quoted is for overall multi-core score, which i7-8700K is about 8 times that of i5-M520, while i7-12700K is about 2.5 times of i7-8700K. Is it surprising consider i7-12700K has twice as many core as i7-8700K? And i5-M520 has only two cores. So per core wise i7-8700K is roughly 2.65 times of i5-M520, while i7-12700K is about 1.26 times of i7-8700K.There is a single thread score of 1111, 2751, 4062 for i5-M500, i7-8700K, i7-12700K respectively. i7-8700K is about 2.48 times that of i5-M520, while i7-12700K is about 1.47 times of i7-8700K, which means i7-8700K is more than twice as fast as i5-M520 at 147% faster, but i7-12700K is only 47% faster than i7-8700K. This 47% faster is probably achieved on the performance core, in the multi-core score, the per core score is only 26% faster, probably dragged down by the 4 economic core.
But operation per sec is not a good real life measurement, invalid when comparing across CPU with different architecture because it doesn't make sense. Which is why there're benchmark based on real world applications. Check sum calculation is a real world application. Compilation, data compression, encryption, video encoding etc are real world applications people used in benchmark such as SPECint that allow comparison to make sense. Word processing of large file with over 15,000 pages, image processing using various filters, software video decoding of 4K resolution at over 100 FPS are demonstrated in the video I posted.
Also, i5-M520 is suppose to be slow. I'm aware it is noticeably slower than i7-8700K which is why I used it to demonstrate slowness. But between i7-8700K and i7-12700K, there is hardly noticeable difference whether running Windows 10 or Linux.