Lights & sounds

Hi guys..just need some help with this song...i can play the intro riff but the problem is that after every repeat..i tend to slow down cause my fingers start to get tired?..any help for improving..

p.s...the song is so much easier to play when u are sitting down rather than standing up..
If you get tired, then go train up your fingers, wrist and forearms la.
You can use those gripppers, just get the normal exercise one instead of those fancy 'made for guitarist' versions.