optimize speed of squarespace

I need to optimize these pages speed from RED to Green on Google

On GTmetrix its grade is C with 5 sec load time, need to increase upto A grade and 2-3 secs.

www.paradiso-island.com
https://paradiso-island.com/spain/madrid
https://paradiso-island.com/spain/ibiza
https://paradiso-island.com/spain/magaluf
https://paradiso-island.com/spain/barcelona