Before attempting to get your 5 year old kindergartner to work faster, which could be an option at some point, it might be wise to get some sense of what is causing this problem. If you have not already done so, I suggest first setting up a meeting with your daughter's teacher to explore some of the factors impacting the issue of work completion.
When you meet with the teacher you can explore some of the following questions: What are the teacher's expectations re: getting the work done at school? (Do you think the expectations are realistic for your child?) Does the teacher expect all the children to always get all the work done? Is your child the only one having this problem? Perhaps the teacher can assist in determining if your five year old's difficulty constitutes a learning problem, an attention problem, a behavior problem, an emotional problem, or some issue that needs to be addressed with special services like behavioral counseling or Occupational Therapy?
Two other avenues to consider in figuring out underlying causes, would be private outside testing to determine the interfering factors; and/or polling other mothers of children in the same class to determine if the trouble is just your child's or is systemic.
Once you do these "assessment" parts, you can determine what needs to happen to correct which problem(s) you identify. Finding strategies to help your child learn to work faster might be the answer, but her speed might only be the tip of an iceberg, the dimensions of which you would want to become aware.
One of the best things you can do for a child is to help her learn the balance between complying with expectations and being an individual. If it turns out that this is just your child's way of addressing her learning challenges, and there really is not anything problematic going on, you might consider working with the teacher to design ways to help your daughter (her student) to be more efficient, without sacrificing quality of work for speed. Most teachers and schools are willing to work within the individual differences presented by their students.
This is a great opportunity to know your child better, and to advocate for her in a way that is empowering for all her future academic experiences.