OP, I did research myself, higher speeds ram do give good boost in fps for games and also keep your CPU less busy. First one not sure if you are gamer, but second one is for everyone because new gen Intel do use more power when utilised at load.
Its a good thing that they are also efficient in idling or in low load levels. I would suggest you to go only 2 sticks of RAM of highest you can put according to your motherboard(after upgrading bios)
I did testing on z790 tomahawk max and I got 8000mhz cl36, and that gave me 30-40 fps more than 6000mhz cl32 that I had for my AMD build.
If you have queries on my testing methods or results or any other related questions, DM me. Also corsair dominator 7200 cl 34 id very good ram in performance to price currently. Try searching IT store sites, you should get cheaper option for high speed.