I suggest to change the title including the Xperia 10 II because, after all the two smartphones are enough similar to go with very similar settings.
This some information that are good for both the smartphone.
Please, install the System Monitor and check the system log with dmesg -Hw. Much probably you will see that your CPUs are not sleeping well but constantly awaken by contest switch (processes that switch the CPUs around).
As soon as, I will have the chance to buy a cheap Xperia 10 III, I will equipped my personal lab with that model as well. If you like to fund raise that buying, the link is here.