Katy's gonna be performing at 4PM.No.. main performer set time time is always 9, at least UK time (unless you're talking about 4pm the next day because knowing Katy and her punctuality skills that prediction would seem quite likely).
I believe they met 4PM EST because that is the time for us eastcoasters.
Actually, it's 4PM UK time. I checked the UK store and it says 4PM. That's 10AM ET and 7AM PT.
I promise you it is never 4PM UK time. I just found out I was wrong too (I checked the iTunes festival app) and Katy's deciding to be a diva with two opening acts, so she's going on at 9:30, which is half an hour later than the other 28 headliners went on. I've been following the festival the whole month it's been happening, no one will ever go on at 4 in the afternoon, the Roundhouse isn't even open at 4, it's a evening thing.