The flexible budget for a company indicates that total manufacturing costs for producing 19,000 units should be $400,000. If the actual costs incurred for producing 21,000 units amount to $420,000, conduct a detailed analysis of the manufacturing cost variance. Consider the breakdown of variable and fixed costs, the impact of production volume on cost behavior, and the efficiency of cost management practices. Recommend strategic initiatives to optimize cost efficiency and enhance operational performance based on the variance analysis findings.