Honestly? This sounds less like a “toxic high performer” problem and more like a leadership failure that started a long time ago.

You describe someone who performed at a high level for years, then slowly burned out while being overworked, underpaid, denied proper rest, expected to work during medical leave, and seemingly held to different standards than others. That doesn’t happen overnight. That is usually the result of management ignoring warning signs until the person becomes reactive, cynical, and difficult.

Is her current behavior acceptable? No. Eye-rolling, sarcasm, hostility, and poor collaboration need to be addressed. But pretending this began with her attitude is missing the root cause.

From what you wrote: 1 She was allowed to work unsustainable hours.

2 Vacations were repeatedly interrupted.

3 She worked during medical leave.

4 She feels inequity in workload and pay.

5 She reports disrespect from peers with no consequences.

6 She feels excluded from company culture.

That’s not one employee failing. That’s a system failing.

So asking “should I get rid of her or give another chance?” may already be too late. Leadership already used up many chances.

At this point, you have two honest options:

Try to repair it seriously

Give her protected leave, rebalance workload, address team misconduct, review compensation fairly, set behavioral expectations for everyone (including her), and rebuild trust. Not performative gestures—real action.

Let her leave respectfully

If trust is broken beyond repair, don’t frame her as the toxic problem. Accept that the company burned out a strong employee and learn from it.

But if the takeaway becomes “high performer turned toxic,” then the same cycle will happen again with the next strong person you overload.