In A15, Anandtech claims the Efficiency cores are 1/3 the performance, but 1/10 the power. They should be looking at (effectively) doubling the power consumption over M1 with just the CPUs and assuming they don't increase clockspeeds.
Going from 8 to 16 or 32 GPU cores is another massive power increase.
I wonder if Apple will give us a 'long-haul' mode where the system is locked to only the energy efficient cores and settings. I us developer types would love a computer that survives 24 hours on battery.
macOS Monterey coming out on the 25th has a new Low Power Mode feature that may do just that. That said, these Macs are incredibly efficient for light use, you may already get 24 hrs of battery life with your workload. Not counting screen off time.
Video playback is accelerated by essentially custom ASIC processing built into the CPU, so it's one of the most efficient things you can do now. Most development workloads are far more compute intensive.
I get about 14-16 hours out of my M1 MacBook Air doing basically full-time development (browser, mail client, Slack, text editor & terminal open, and compiling code periodically).
I know everyone's use case is different, but most of my development workload is 65% typing code into a text editor and 35% running it. I'm not continually pegging the CPU, just intermittently, in which case the existence of low power cores help a lot. The supposed javascript acceleration in the M1 has seemed to really speed up my workloads too.
This is true, but it's not worst case by far. Most video is 24 or 30 fps, so about half the typical 60 hz refresh rate. Still a nice optimization path for video. I'm not sure what effect typing in an editor will have on screen refresh, but if the Electron issue is any indication, it's probably complicated.
Going from 8 to 16 or 32 GPU cores is another massive power increase.