I had a co-worker survive the PIP he was put on. He was very thorough coder, but not particularly fast (when he delivered code it always worked really well, comforting for radar software), so when he was put on a new project that didn't value that over scheduling he had to adjust. Between that and a change of language he ended up on a pip. He lasted 5 years after that and one round of layoffs, before being let go in a second round. He's somewhere else now.