Large company, performance is based almost entirely on feedback from peers and those you report to with check-ins every 6 months. Overall score from 1-5 with a 3 being "meets expectations" and the most common rating by far.

The problem is that the feedback from superiors seems to be weighted much higher so the peer feedback is almost useless so don't bother mentoring or helping someone get back in front of their tasking. This leads to a lot of I'm-working-so-hard theatrics instead of actually being efficient/effective and delivering product.

Combine this with "suggested targets" (quotas) for the number of people in each 1-5 bin, you end up with the usual stack ranking problem that getting on the shittiest project (and keeping it that way to ward off competition) and making it damn clear to your manager that they can't live without you is the best strategy.