Graphics, Throttling and Storage Performance
The HTC U11 is slightly different from other S835 handsets we've reviewed in that it has a 1440p display. The Xiaomi Mi 6 and OnePlus 5 both have 1080p displays, so it's no surprise the U11 brings with it a 45% performance reduction in on-screen workloads. However, when comparing raw offscreen data, the S835 performs as expected.
Compared to the HTC 10 with the same display, we're looking at 23 percent better performance on average in GXFBench's onscreen tests, and 45 percent better performance overall.
The HTC U11 does throttle, like most smartphones these days, approximately 5 minutes after encountering a sustained GPU-heavy workload. The level of throttling is significant too: as soon as throttling kicks in, performance is reduced by 37 percent. While sustained performance is a bit higher than other S835 handsets like the Xiaomi Mi 6, the U11 throttles harder than the HTC 10 by a significant margin. In fact sustained performance from the U11 is just slightly lower than the HTC 10.
Storage performance disappointed me, and that's primarily down to weak random performance. Random writes are a significant regression and fall well behind nearly every other device I've tested in the past two years. We're also in a world now where many other flagships are pushing above 40 MB/s random reads, but the U11 only manages 25 MB/s in that regard with mid-table sequential performance.