Ageism and age discrimination can be a real problem when you're over 50 and trying to find a job. No matter what your qualifications and enthusiasm for a position, some employers won't seriously consider you if your resume makes you look too old.
Performance improvement plans, or PIPs, are part of an employer's paper trail. PIPs are supposed to be tools that employers can use to address deficiencies in an employee's work. They're also supposed to be tools that help the employee understand exactly what he or she has to do in order to bring his or her performance up to expectations.