Not sure you can look at it in isolation, when considering a set of rules with various differences. For instance, as mentioned the cars are significantly heavier this year, which will have some effect on the maximum performance, but with only 2/3 of the fuel the maximum weight delta between the start of the race and the end of the race is lower and in 2013. As I mentioned before, the prior rules had a larger gap between their slowest race pace and their maximum race pace (by virtue of fuel usage and tire characteristics) while these new rules are operating in a narrower band between slowest and fastest pace.
The tires for 2014 are more durable, but that tends to mean giving up a little on grip / speed as well. Last years tires would probably yield a slightly higher peak pace but then they'd be shot in no time by virtue of the torque demands and increased weight.