The OnePlus 9 Pro, even though it advertises itself as using the latest LTPO OLED technology as Samsung’s Galaxy S21 Ultra for example, still suffers from notably worse power characteristics and worse power efficiency. In our web-browsing battery life test, even with this performance crippling mechanism in place, with both devices at 120Hz under the same test conditions, the OnePlus 9 Pro achieves 11.75 hours of runtime, versus the S21 Ultra’s 13.98 hours, the latter which runs at the SoC’s full performance potential.

While application behaviour and performance varies case by case, the one aspect that holds true in almost all scenarios is that the OnePlus 9 Pro doesn’t deliver on the full characteristics of the Snapdragon 888. In blacklisted/detected applications, when and if the X1 cores are being used at all, frequencies beyond 2.38GHz are unreachable save for brief booster moments. The vast majority of apps fall back to 2GHz Cortex-A78 cores. This is all a bit ironic as the reason the larger more performance X-series cores were created in the first place was to serve high transient response performance workloads, something they’re not allowed to do here.

https://www.anandtech.com/show/16794/oneplus-9-performance-examination/

Response

Smartphone processors have continued to become stronger every year, enabling software developers to develop more powerful and sophisticated apps, in turn, helping users to do more things with smartphones than ever before. In recent years, the performance of smartphone SoCs has reached a point where their power is often overkill in certain scenarios for many apps including social media, browsers and even some light gaming.

With this in mind, our team has shifted its attention from simply providing sheer performance to providing the performance you expect from our devices while reducing power consumption and heat dissipation. To be more precise, we want to match each app with the most appropriate performance it needs.

In the case of the OnePlus 9 and 9 Pro, when you open apps or heavy games, the Snapdragon 888 processor, including the super powerful X1 CPU core, will run at full speed to provide the best performance. But with actions that do not require the maximum power, like reading a webpage or scrolling through Twitter and Instagram, it’s not necessary for the CPU to run at almost 3GHz to do that smoothly. The OnePlus 9 and 9 Pro reduce the CPU frequency in these scenarios to reduce power consumption and heat dissipation while maintaining a smooth experience.

The OnePlus R&D team also maintains a list of applications – based on the most popular Google Play Store apps – that we try to optimize, including some of the apps you know and love like Chrome, Twitter, Zoom, WhatsApp, Facebook, Instagram, Snapchat, YouTube, Discord, Microsoft Office plus our own apps. All of this optimization is only finalized after our testing team makes sure the actual user experience is not negatively affected.

https://forums.oneplus.com/threads/insight-into-oneplus-9-series-processor-and-app-optimization.1467338/