Yeah but this is Intel, they're not capable of doing something the most efficient way possible. E cores use less power than P cores, but that doesn't mean they're very good at getting the job done using the least amount of power. Currently (using Intel's management) 12th and 13th gen start a task on the P cores, and if it runs for longer than X time it gets shifted over to the E cores where it can churn away. Meteor lake has 3 stages of things since there's P cores, E cores, and LP E cores. If I remember right Meteor lake starts a task on the LP E cores, then shifts it to P cores, then shifts it to the E cores if it's taking too long. But Intel likes to blast the power away with turbo boost and runs the E cores way past their actual efficient zone unless you wrangle them back down. Sometimes it's faster to blast the task away on the P cores then return to idle, other times letting it churn away on the E cores forever is the best way.
Also all those extra cores being active still uses power. So if you went from a 4 core CPU to a 4 + 4 cpu now you have all the same power draw as the old one, plus the extra 4 efficient cores sipping at even more power. I think that's where 12th gen really suffers the most.
Lol, a lot of wrong information here. 30 mins only, wth. There must be something really wrong with your battery or setup. I am currently writing this from a Legion 5 Slim laptop with 13th gen i7 CPU with 20 cores total, and I get more then four and a half hours of battery life with 85% display brightness in power saving mode.
P.S. this is why I take a lot of information from Linux "pros" like you with a grain truck of salt
I use windows on this machine, and only because windows gets better battery life generally on newer hardware.
I can get more than 30 minutes of battery life. But doing any sort of work on an i9 and having an rtx 3080 active drains the 90 watt hour battery pretty quickly. If I do nothing I can get almost 10 hours of battery life, but that's doing nothing. I get 3 or 4 doing light tasks, or 2 or less doing my normal work with the GPU off simply because I keep the CPU active and Intel CPUs get garbage battery life active. My AMD latptop gets 4+ in the same workloads, and my M1 macbook gets 6+ emulating the same work load. As a person I'm just incompatible with Intels race to idle, and their architecture is based on that.
They're not really made for power efficiency, but rather space efficiency. ~4 E-cores fit into the size of a P-core.
They're there to boost multi-core performance without having a huge die-size or increasing latency in the P-cores when doing lightly threaded tasks, essentially.