I'd say it's not the amount of computation being done, but the way it is done. A calculator is not conscious no matter how fast it is.

A human brain, capable of catching itself making a mistake, is conscious.

An LLM, with both its code and HW being written on stone, is not. If you input the same string, you get the same string (except for some ramdomizer in the mix). It cannot change the output and it cannot detect the processing of the output.