The best way to avoid having to fire underperformers is not to hire them. This is why we would rather our hiring process generate more false negatives (people we should have hired but didn’t) than false positives (we shouldn’t have hired but did).
Test yourself: If you could trade the bottom 10 percent of your team for new hires, would your organization improve? If so, then you need to look at the hiring process that yielded those low performers and see how you can improve it. Another test: Are there members of your team whom, if they told you they were leaving, you would not fight hard to keep? If there are employees you would let go, then maybe you should.