Error selecting champion (and other terribad tiltworthy client issues)

I basically only play Nami now but I was hovering around other champions and literally when there was 15 seconds left it snapped to the countdown at 8 seconds and when I click back on Nami it says error selecting champion??

On top of that, I feel like this client is so insanely terribly optimized, I upped all the specs possible on my Mac and the client still lags and has delay, no matter what I do, browsing profile and collection, or in champion select changing runes.

On the topic of runes, it always has a 3 to 4 second lag between clicking in to select which runes I want, meaning I literally cannot change runes in champion select if I have to.

And to add on top of that even further, everytime it ticks down to 10 seconds for the countdown, it lags and snaps to 8 seconds and the game starts at 2 seconds.

Why has the client always been so insanely terribly optimized? And yes, I do use low spec mode so Riot should have no excuse for these delays