Google Pixel 9 Pro XL testing reveals Tensor G4 thermal throttling with 50% performance loss

Google's Tensor SoCs have long been the subject of criticism for their mediocre performance and thermal throttling. The Google Tensor G4 in the newly announced Google Pixel 9 Pro XL seems to suffer even more than its predecessor in this regard. 

According to a post by @callmeshazzam on X (post embedded below), who ran a CPU Throttling Test app on his Google Pixel 9 Pro XL (curr. $1,099 to pre-order on Amazon), the Tensor G4 loses up to 50% of its CPU performance when under sustained load. The stress test shows the frequency of all eight of the Tensor G4's CPU cores across the duration of the test, and it only takes about three minutes of 100% load before the CPU starts throttling. 

The Pixel 9 Pro XL's CPU reaches maximum throttling at around the four-minute mark, at which point it appears to have lost close to 60% of its performance. According to the performance readout, the Tensor G4 maxed out at 341 GIPS (giga instructions per second), with average performance coming in at 246.6 GIPS. When it was throttling the hardest, the Tensor G4 in the Google Pixel 4 XL only achieved 145.5 GIPS — only 42.6% of the maximum performance. After hard throttling, the performance seems to creep back up to a stead state of around 65% of the maximum.

Taking a peek at the frequency chart, the Tensor G4's performance cores dipped to lows of 1.32 GHz, while the efficiency cores reached a minimum frequency of as low as 570 MHz. Google has yet to release official information about the Tensor G4, but earlier Geekbench 5 results indicated that the Tensor G4 has one core clocked at up to 3.1 GHz, three cores clocked at 3.6 GHz, and four efficiency cores clocked at 1.95 GHz. 

Of course, instructions per second isn't the best performance metric, and, being a stress test, the performance loss is worst-case scenario. In our testing of the Pixel 8 Pro's Google Tensor G3 with 3DMark, we found performance degradation on the order of 12–14% thanks to throttling. 

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