AWS DynamoDB Optimization

We are an ERP SaaS company newly launched. Our application is hosted on the AWS cloud and we had it built via contractors. One section of our application uses DynamoDB + S3 to store and retrieve files attached to records. This setup has performance problems and we are looking for someone we can engage for a short fixed-rate project to improve the performance of this structure. The DB only has two tables in it but our knowledge of the AWS + DynamoDB structure is limited.