If your team-members are taking long time to serve every customer, which is hampering the efficiency level, how would you solve it?

There are two options; (1) Approach them professionally & politely without causing interruptions or caos, kindly & warmly ask them if they might need to help in any case; if they accept, help them without humiliating or minimising them. (2) You can approach them in their free time creating a pleasant & productive dialogue with a view to understand & help them improve, be free, empathetic & compansonate with them if you are yield any good results. Kindly advise them & give them some tips on how to improve, if they sobber & conscious enough, they will surely appreciate your efforts