Player jumps a different height when changing player aspect ratio (resolution) [Edit CPU also involved]

I have a character controller with a certain gravity and speed to run and jump. When I run the game in the unity player, it jumps at certain height, but when I maximize the player window the jump is more lower, is like half the original jump.

If I change to different resolutions in the player the same thing happens the jump vary its height.

Do you know why does this happen? Please tell me if you need some code or if it is a general issue.

Thanks.

Update. Aparently the problem is worse, you see, if the computer clogs with heavy process, like opening a lot of youtube videos to decrease my computer performace. the player I use JUMP LOWER than if the computer has a lot of extra cpu free.

So if I have cero processes running my player jump with a low height .... if my computer is slow the player jumps higher

I use time.deltaTime for everything ! this should not happen!!