When you turn on a television set. What the heck is going on that it takes 10-15 seconds to see a picture? For Christ sake, a set manufactured in the 2002 takes just as long to “warm up” as a set made in 1960. What goes on once you turn it on that it takes so long to be functional? (Yes 15 seconds is a long time. It’s the 21st century for crying out loud!) They used to make “instant on” sets. Whatever happened to them?
The picture tube in your set is a <gasp!> vacuum tube that requires heat to operate. There’s a heater inside the tube to do the job, but it takes a few seconds to get it going. The old instant on sets kept the heating filament on even when the set was turned off, but the old timers I know in the repair biz have told me that they were inefficient, or a fire hazard, or both… I don’t know if they really were a fire hazard, but I could believe the inefficiency…
My tv was free out of a friend’s garage, and looks to have been made in the mid 80s. It doesn’t take any time at all to warm up. I don’t know what you’re talking about.
I have changed the title of this thread from Why does it take so long… to Why does it take so long for a TV to warm up? In the future please choose more descriptive thread titles.
I have a new Toshiba 27" TV and it takes about 4 seconds for the picture to appear. 
Here’s the first relevant google result I found:
Instant-on TVs
Note that if you have an “instant on” tv and its plugged into a cable box and you use the cable box on/off to turn your set on/off then you no longer have an “instant on” tv. Yet another reason why tvs with this feature are no longer a good idea.
My 32" Toshiba takes approx 4-6 seconds to fill to full brightness from a cold start. I think you might want to look into different brands if your set is taking 15 seconds or possibly switch to decaf.
You can call the manf & ask them. Maybe you can get an exchange if its new & takes too long?
You could plop down the big bucks on a plasma tv, or a nice large LCD monitor for the computer and add a TV tuner. Course any decent new TV sould only take 4-6 like others have mentioned before. My 27" Sony is like this. It’s about 2 years old. My 16+ year old 19" Hitachi also takes only a few seconds to warm up. It has a few other problems, but it still warms up quickly.
I take it back. I make it to be about 4 seconds. I never noticed, I guess because I was involved in sitting down while the picture was black.