What event showed how inefficient the Confederation Congress was and accelerated the moves to revise the Articles of Confederation?

Shay's Rebellion.

Explanation:

Shay's rebellion was an armed rebellion of the farmers who were former war veterans and took up arms because of the heavy taxation and foreclose of their farms in the region of Massachusetts. To pay war debts States implied heavy taxes which were greater than, that were in the times of Britishers. Congress's inability to collect taxes was exposed and shay's rebellion became a major reason to look for the Constitution of America which increased the power of government.