90 seconds as measured by non-realistic volunteers in Toulouse and/or Everett who aren't actually afraid for their lives :(
I'm not sure if you think that people afraid for their lives would be faster or slower.
They would most definitely be slower because of the panic and people pushing and shoving each other compared to an orderly and rehearsed exit
I learned the other day that to simulate panic at some point they started giving money to the passengers who got out first. They said nothing about the amount, but as far as I could understand it actually worked.
Edit: this was in a program about the Manchester plane fire in 1985 where 55 people died. The details are from the part about the investigation after the fire.
The first half to leave the plane are given $50 or so. According to people who have had to deplane in an emergency, this produces identical behaviour.
Maybe do-able. Gotta run an experiment to find out.