HMI display design with SAMA5

[Skydec]

Hello,

I'm a bit new to the ARM processors (used PIC before) and I'm looking for a way to build HMI display.
I tried to use linux for this and it works, but Linux is to slow to start (I'm looking for something instantly)

Is there someone who has experience with building a GUI (I think bare bone) and what kind of development tools are recommended to make the gui and use the display.
It's not that it must be plug and play, but some visual components like buttons, panels, images etc. should be available hopefully so that it looks professional.

What software is recommended for this.

Thanks in advance.