Chinese Grand Prix (Shanghai):
2004: fastest lap Michael Schumacher - 1:32.238
2014: fastest lap Nico Rosberg - 1:40.402
Conclusion: 10 years later, the best Formula 1 car is more than 8 seconds slower on this circuit. That is huge, and tells a lot about the negative impact of regulation changes on this sport.
Later edit: or, to go further with this rant:
2004: Rubens Barrichello (winner) completed
56 laps in 1:29:26.985
2014: Lewis Hamilton (winner) completed
54 laps in 1:33:28.338
Which means that in 2004 Barrichello would had time to stop at the pit, get off the car and gulp a burger, get back in, run 2 extra laps (!) and still win against the best car+driver of 2014...