I have a computer with a Celeron 1.6 GHz processor and 512 MB DDR2 RAM, and I love this distribution of Linux, so I would like to know if there is some way or maybe a program that can make Ubuntu more lighter.
Your options are limited... in other words, you need to upgrade your processor...
upgrading your ram might help too but I doubt it.
You could also consider using a lighter Desktop enviroment. such as lxde
I'd recommend Lubuntu.