def METHOD_NAME(self, fixture, start_timestamp):
    event = json.loads(self.load_fixture(f"events/performance_problems/{fixture}.json"))
    for key in ["datetime", "location", "title"]:
        del event[key]
    event["contexts"] = {
        "trace": {"trace_id": "530c14e044aa464db6ddb43660e6474f", "span_id": "139fcdb7c5534eb4"}
    }
    ms_delta = start_timestamp - event["start_timestamp"]
    for item in [event, *event["spans"]]:
        item["start_timestamp"] += ms_delta
        item["timestamp"] += ms_delta
    return event