Performance optimisation (accidental)

So, I updated the game to Unity 2021.3.17f1 mainly because the hard drive where my Unity editor installs are was running out of space, and the game is much, MUCH smoother now.

I was getting what appears to be memory leaks, so the performance would dwindle gradually until the game was running below 30 FPS after a while, but it currently runs at 75-90 FPS consistently.

The UI appears to no longer slow down the framerate either; displaying a season calendar of 300+ games would do that.

Saving your league - wether a tiny 4-team or a big 32-team league - is also lightning-fast.

So, all in all:

• Faster FPS everywhere
• Faster league creation and saving after each game
• Lesser impact of apparent memory leaks on performance over time

Cheers