For historical perspective, Core 2 Duos are from 2006/7. And T7200 is a laptop version, slower than desktop equivalents of the same era.
Desktop CPUs are still much, much faster than phone CPUs. Here's a table with lots of numbers:
http://www.computingcompendium.com/p/arm-vs-intel-benchmarks...
The iPhone 5s, with the "desktop class" A7 chip, has about 15% of the computing power of an i7 4770k, by this benchmark.
Personally, I don't use mobile devices - neither phones nor laptops - for compute-heavy operations. Everything from compilation to video transcoding takes way longer than on a decent desktop. Phones are not close to threatening that yet, not by a long shot.
Trivial work, like text editing, light photo manipulation, sure. Anything that could be done on a PC 15 years ago, sure. But they're nowhere near one another.