Slow Scale - Create a normal Scale

[i3Designer]

I have a sprite, and I want to make it bigger and bigger, i do:

this.spirte.width = this.sprite.width + 10;

this.spirte.height = this.sprite.height + 10;

After a few seconds, everything becomes very slow and it is normal, how can I do?

I have also tried this way:

this.spirte.width = this.sprite.width * 0.008;

this.spirte.height = this.sprite.height * 0.008;

 

but is equal.

I can not create a solution to scale with the same speed.

PS: I am creating a fake 3d, the sprite is moving ever closer to the camera