In our bathroom we have a 20 watt IP65 fluorescent light fitting, installed
a couple of years ago.

I am becoming neurotic about the fact it takes 5-10 seconds to switch on
(and always has).

Pics he

http://www.hernibles.com/light1.jpg
http://www.hernibles.com/light2.jpg

Is it possible to swap some component of this light to make it "quick
start"?

Wisdom appreciated.