I know what you talking about. Back in the past aimbot was such a godly thing; they would hit no matter what with extreme precision. If you said head, then it would be head, neck then neck, chest then chest, no it was like magic bullet of how precise aimbot back them was, but today aimbot is surely lacking in precison, is the enemy moves a bit the shot will go all over the place, there even stances where you enemy is just standing there, you shot and hit a headshot while you have marked to shot chest. Is a mess. I understand why you would think is a processor issue, but it is not, is either poor coding, game limitation due to protection or just how that type of aimbot works.
When I speak about poor coding I we had a primer exemplo on this forum, the PUbG Lite AImbot that worked fine close-range but was completly useless in mid to long range shots. Its nos due too lack of processing power, is poor coding, in the code there is no condition to handle distance and subtle movments.
By limitation of the caused due to game protection, is a bit more complicated to explain since I personaly don't understand much, but in coding we use function to tell the program what he should do, a lot of those function are already know, but people still find/create new ones, but as those got known they got either patched of listed in the anti-cheat. A clude exemplo of this would be mousemove(name change depending of the lenguaje), a funtion to move the mouse, nowday any decent anti-cheat has it listed and insta ban if they detect it being used, and this function was used to force you mouse move to the target. So people have to think of different or new method, which are often not so good as the old ones.
Lastly, the type of aimbot, some aimbot works not by getting the informations from the client, they work by detecting the pixels, this one kind of cheat is the one tha rellys the most on CPU power to work better, but is not that much, if is poor coded (such a colour precision being bad) it will not be good no matter how much processing power you got.