You necessarily need to increase the performance of all subordinates. Your company is failing and the main share is unfortunately staffers. For a long time you watched the performances of all subordinates and found great shortcomings. This must change immediately. You probably can't solve this complex problem yourself. It will be a lot better to find a capable externist who can establish the desired order in your company. If you want a change, you will have to invest a little money into subordinates. However, you will see that this investment is guaranteed to be worthwhile.
Monitor regularly and carefully the performance of your subordinates
You're just revealing the hidden reserves. You feel that people in the company have recently failed to fulfill their duties properly. That's why you hired an externist who, of course, confirmed your presumption. So it is time to get harder. You were a very tolerant boss, and people began to abuse it appropriately. But that will change soon. Employee evaluation was absolutely necessary in your case. You believe that you will succeed in restoring your company's proper order.