Full disk encryption on Nexus 6 leads to 62.9% drop in random read performance
Encryption and Storage Performance in Android 5.0 Lollipop — As alluded to in our Nexus 6 review, our normal storage performance benchmark was no longer giving valid results as of Android 5.0.
Context & Ripple Effects
Google made full-disk encryption a headline feature of Android 5.0 Lollipop's security push, and the Nexus 6 was the first flagship to ship with it enabled. AnandTech's Nexus 6 review had already flagged that standard storage benchmarks were returning invalid results on the device — this follow-up explains why: the always-on crypto layer sits directly in the storage data path.
First-order effects
- Nexus 6 owners get security by default but pay for it in responsiveness — random read performance falls 62.9%, meaning app launches and UI loads feel slower than the same hardware unencrypted.
- Reviewers and buyers lose a reliable yardstick: AnandTech's normal storage benchmark no longer produces valid numbers on Lollipop devices, so published comparisons of encrypted flagships are measuring the crypto layer as much as the flash.
Second-order effects
- SoC vendors face pressure to accelerate AES in hardware rather than software; Google's later decision to make encryption default only where AES throughput exceeds 50 MiB/s (Marshmallow's conditional mandate) is a direct response to exactly this kind of performance cliff.
- Benchmark suites must adapt or lose relevance — if the market interface for phone reviews can't distinguish NAND quality from encryption overhead, vendors shipping fast crypto gain an unfair appearance advantage.
Third-order effects
- The episode foreshadows the architectural split that arrives with Nougat's file-based encryption (which AnandTech's analysis frames as progress but still years behind iOS): encrypting per-file rather than whole-disk lets hot data paths stay fast while preserving security defaults.
- If security-by-default becomes table stakes across Android, encryption overhead shifts from a user-facing tradeoff to an SoC design requirement — crypto acceleration becomes a competitive spec alongside CPU and GPU, and reviewers need new methodologies to separate the two.
The trend: Mobile platforms are converging on always-on encryption, forcing the industry to treat cryptographic throughput as a first-class hardware specification rather than an optional software layer.