Nexus 6 Performance With Android 5.1

Web Browsing Benchmarks

The update does not seem to impact JavaScript performance in our browser benchmarks.

MobileXPRT 2013

MobileXPRT 2013 shows a worst case scenario for the updated Nexus 6. All of the content related tests read and write small amounts of data to disk and don’t fully task the CPU cores. The lower scores here likely reflect the loss of thread migration and a small reduction in storage performance for certain workloads (more on this in the next section).

The user experience tests are unchanged except for Browser Scroll, which sees a significant reduction. Investigating further reveals that the Nexus 6, running either Android 5.0 or 5.1, sets the CPU frequency to a fixed 1497MHz during UI interactions such as the List Scroll, Grid Scroll, Gallery Scroll, and Zoom and Pinch tests. When running 5.0, the Nexus 6 sets the CPU frequency to a minimum of 1497MHz during the Browser Scroll test but frequently spikes to its max frequency of 2649MHz. The 5.1 update changes this behavior, with the CPU governor frequently letting the frequency drop to 300MHz during the Browser Scroll test, which accounts for the lower score.

To see if these results are valid when using a real web browser, I fired up Opera and loaded a simple page without ads (Wikipedia’s home page). I then continuously scrolled up and down while monitoring the CPU usage and frequency. The Nexus 6 running the 5.0 release locks the CPU frequency at 1728MHz with two cores active. Running 5.1, the CPU frequency is locked at 1497MHz, which is the same frequency as the Browser Scroll test and equal to the touch input boost frequency.

For comparison, the Samsung Galaxy Note 4 running Android 5.0.1, which also uses a Snapdragon 805 SoC, behaves quite differently during these tests. The CPU governor allows the frequency to bounce around quite a bit during all of the user experience tests except for Browser Scroll, where the frequency is set to 1190MHz. With a lower average CPU frequency, the Note 4 performs worse than the Nexus 6 in these tests. I also performed the same basic browser scrolling test in Opera on the Note 4, and it also set the CPU frequency to 1190MHz.

These results suggest that UI responsiveness remains essentially unchanged with the OS update, with the Nexus 6 maintaining its lead over the Note 4 in this critical area. However, these benchmarks fail to capture the effect of having all four CPU cores active all the time. In the real-world, there will be several background tasks running, performing tasks like checking for new email, social media news, and app updates. It’s these uncontrolled scenarios where having the additional cores available will help balance the load and help keep these other processes from interrupting UI update threads. So while peak UI responsiveness is unchanged, or even slightly reduced, the effective responsiveness seen in normal use may be better with the 5.1 update.