If they are not performing well, then it's usually that they don't know how to do the task. I like separating my R&D. Researching during Development can be frustrating. Especially if the deliverable of development is time bound. So before work, we only use well known tools & methods. If we are going to experiment, I like experiments ran by themselves where failure doesn't bring any stress. After learning from the experiment, we only bring one new major technology into the picture at a time.
I also give pep speech every weekly team meeting. I can't help it. Everyone has greatness in them provided they are willing to work it out! One must do the work, one must stay gritty in the difficult times. One must find meaning in all work that is done, and that meaning should not just be useful to us but to the world at large (our customers) A positive and growth mindset is very important so I make sure to nurture and cultivate that in the team. Our rallying cry is "Challenge accepted!"