Toxic High Performer: What To Do When They Deliver But Destroy

Your top performer hits every target but makes everyone else miserable. Here's how to handle a toxic high performer before it costs you the team. Listen now.

If your best performer is also your biggest problem, you're not alone — and you're not imagining it. Toxic workplace culture costs the UK economy over £20 billion a year, and 27% of SME employees have quit because of it. When someone is brilliant at the job but brutal to work with, it creates one of the hardest calls a business owner or manager faces: do the numbers justify the damage?

In this episode, Claire and Sarah work through exactly what to do when you've got a toxic high performer on your hands. You'll learn why hitting targets alone doesn't equal good performance, how to build the evidence you need before having the conversation, and what happens if the behaviour doesn't change. Whether you've been avoiding this situation for months or you're right in the middle of it, this episode will give you a clear, practical path forward.

• Hitting targets is only half of performance. What someone delivers and how they deliver it are both part of the picture. A toxic high performer who damages relationships and drives people out is not fully performing, whatever the numbers say.
• The commercial cost is real. Every good person who leaves because of one difficult colleague costs you recruitment fees, lost knowledge, and a signal to the rest of the team about what you're willing to tolerate.
• In small businesses, the impact lands harder. When your team is five to twenty people, one person's toxic behaviour shapes what everyone else thinks is normal. It becomes the culture.
• Evidence before the conversation. Vague feedback does not land with high performers. You need specific examples of behaviours, a clear picture of the impact, and an equally clear description of what good looks like going forward.
• Use what you already have. Competency frameworks, company values, and 360 feedback aren't just nice-to-haves — they give you documented standards to point to when the person says ”but I'm generating the revenue.”
• If the behaviour has been allowed for years, the individual deserves context. It's not fair to suddenly score someone down on behaviours they've never been pulled up on. Hold the mirror up, explain the impact, and give them a genuine chance to change.
• At some point, it becomes a choice. If genuine attempts to address the behaviour don't work, the question is what you're willing to accept in your culture — including the reality that anyone who works under that person is likely to leave within six months.

• [00:00] Is a toxic top performer really performing?
• [01:55] Why businesses avoid the conversation
• [05:30] What to do if they push back
• [07:19] Competency frameworks and 360 feedback
• [10:07] How to start tackling long-standing toxic behaviour
• [12:23] PIPs, documentation, and formal process
• [14:49] Small business vs big business: the difference
• [17:24] When behaviour doesn't change: the final decision

References

1. Breathe HR Culture Economy Report — referenced for UK toxic culture cost data and SME employee turnover statistics: breathehr.com

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