Always loaded in memory . what is that ?

in resources there is an option for each image always loaded in memory ? what does that do ?

ok wow … when i enabled this and test it on my phone . the game feels so much smother and faster with stable fps … there is still fps drops but it’s minimum . also if anyone have any suggestion to make the game run at optimal performance that would be great and i have to notice that :-

1- no pixel perfect is active
2- there is timers on every collision (0.1 sec)
3- today i removed every useless event and made parent and children events (i think that’s what it’s called)
4- no smoothness
5- game resolution is 854*480

I tried every thing to make it run at full speed but it won’t even after all of that .