Ubuntu 13.04 on MacBook Pro 8.2 Single Boot?

[M477H145]

Hello,

I'm a newbie at Ubuntu so don't judge me on my lack of knowledge.

I recently installed Ubuntu on my MacBook Pro.
I've deleted the original OSX files by replacing it with Ubuntu during installation.
Now I'm facing some issues with the booting delay and the Mac being 80°C whole the time.

I read that having installed it with an EFI Boot is required.
Is there any way to install this EFI without having to lose the files I currently have on Ubuntu?

Thanks for any help!

[2F4U]

I would rather suspect the graphics card being responsible for high temperatures. What graphics card is it and what graphics driver are you using?