Question about Intel Core i7-9700K

No. The performance differences are almost = 0. Depending on the performance, the 9700k performs a little bit worse or a little bit better than the 8700k. In any case, not nearly enough to make up for the price. Not that it's particularly expensive, but going from an 8700k to a 9700k isn't worth the money. Better wait at least 2 generations or buy something really powerful if the 8700k isn't enough for you.

No