First, don't panic: almost every business goes through this moment. Conduct an audit of the team: who is really working, and who is just taking up space. Talk honestly with employees. Think: if you were hiring people again today - who would you definitely take? And who wouldn't?
Second, build a culture where responsibility is the norm, not a feat. Where ideas are heard. Where everyone understands how their work affects the common cause.
And yes, if you feel that someone is slowing down, don't be afraid to part ways. Ask yourself one question: "If this person quit on their own, would I be happy or upset?" The answer will help you make a decision.
Business is not about patience, it's about speed. And your team members are either an engine or a ballast. The choice is yours.
How to build an effective business team - read
here.