What is lame is people posting ignorant comments as Anon Cowards.
Apple has control of both the hardware & the software & has optimized both to make use of FDE as painless as possible. This is clearly not the case in Android.
Stealing from Seillac's comments on ARS:
"Apparently, Google has not merged the various drivers that optimize Qualcomm's QCE module for encryption and decryption into AOSP. The generally-assumed reason is that this code is proprietary. Without these optimizations, the Nexus 6's hardware decryption module on the Snapdragon 805 is essentially hamstrung."