uhh, in 2015 a i7 had 4cores, boost of around 3.4
in 2018 a mobile i9 had 6cores/12threads, bost of around 4.8 (so lets be reasonable, thermals might let us keep 3.6).
For a super optimized parallel load you could totally see more than 2x speed up.
But yeah... why do that on your laptop?