Is there any energy wasted through USB cables due to data sync when plugged in wall charger Is there any energy wasted through USB cables due to data sync feature when plugged in wall charger.

The thing is, I've heard of some engineered USB cables such as "SONICable" and "Doubletime" which can allow your smartphone to charge its battery twice as fast when you plug it to your computer USB port.
That's accomplished by some smart PCB that talks to both your smartphone and your computer, and tell it to eliminate the data sync feature, and focus all energy to charge the smartphone.

https://youtu.be/EBWQAClwjfc

So, I was wondering if it also can speed up the charging process when it's plugged into wall charger...
According to this article (sorry, german only) the iPhone - attached to a wall charger - detects that no data sync is possible and charges with the full specified power (±1000 mA).

Attached to an USB 2 interface (like your Mac) the power is reduced to ±500 mA to not interfere with the data stream.

Now the smart PCBs in USB cables as "SONICable" and "Doubletime" come in: Attached to an USB interface they trick the charging controller by simulating a wall charger on the data lines and the charging power is then increased to > 500 mA again if the interface can deliver that. As mentioned by bmike ♦ USB1/2 is specified with 500 mA and USB3 with 900 mA. But most interfaces have some upwards tolerance and deliver more power than specified and thus decrease charging time.

Due to the non-linearity of the charging process the charging time will NOT be halved though!

The conclusion of the linked (german) post: 

In some combination (USB3 - Tablet, not necessarily Apple devices!) charging speed will be increased up to 100%. In most cases the charging speed increase is lower than 100%. Attached to a wall charger no significant speed increase is detected.

To answer your question(s): 


Attached to a wall charger charging speed shouldn't be increased noticeable using the two mentioned cables.
No energy is wasted through USB cables due to data sync when plugged in wall chargers.