Bro, i reinstalled java different versions etc. the fact that the mirror client only runs in 32 bit and converts 64 to 32 causes a significant reduction in performance.
MAC OS forces 64 bit so therefor the mirror mode runs in 64 bit which is why a shitty old mac will outperform a literal RIG of a pc when it comes to mirror mode frame rates.
This is an issue that should be looked into as way more people use windows due to macOS hardware restrictions.