My understanding is that cheaper devices (at least historically) tended not to have a discrete chip for handling GPS, which could run extremely efficiently and

My understanding is that cheaper devices (at least historically) tended not to have a discrete chip for handling GPS, which could run extremely efficiently and at very low power, and instead were forced to use the CPU to do the work - contributing to the reputation of being slow and power inefficient. Modern devices do the sensor fusion on CPU but it's just polling the GPS chip for coordinates as required, which handles all the actual signals processing stuff.