Looking for a story; probably from the 80s or earlier.
An AI in some kind of jungle/post apocalyptic wasteland is living in a boring, isolated area. He has the ability to edit his own memories, and also the ability to control his own sense of time. Over the years, he's slowing his perception down more and more, and is approaching the point of completely stopping himself. Also, he's edited / deleted so many of his memories that he's no longer sure what's real. He'll do big projects, then delete the memory, and now whenever he starts something he's unsure whether he's tried it before & already deleted the reference. He's also quite proud of the level of earthquake-proofing his emplacement is built to.
The central image of the story is him slowly circling around, slowing himself more and more, and approaching a complete stop.
There may be something that happens with a primitive human approaching the building he's embodied in and asking him a question, which temporarily wakes him up.