It happens because of two main reasons, firstly is just because of bloat - software/websites are less optimised or doing more because they expect newer and better hardware. The second thing is the intentional throttling of the hardware by the operating system in response to reduced battery life to maintain longevity. basically if the battery is at 50% original battery, to maintain 10+ hour battery life, the device has to use less power - and the way it does that is by lowering the performance of the hardware.
It happens because of two main reasons, firstly is just because of bloat - software/websites are less optimised or doing more because they expect newer and better hardware. The second thing is the intentional throttling of the hardware by the operating system in response to reduced battery life to maintain longevity. basically if the battery is at 50% original battery, to maintain 10+ hour battery life, the device has to use less power - and the way it does that is by lowering the performance of the hardware.