How to improve performance when uploading absence data from 3rd party using CI

Some groups of employees are using 3rd party applications to enter their time and absence information. We've created a custom service operation handler using Component Interface, but it takes significant time loading data into GP_ABS_EVENT table. We've noticed that the CI is designed to look historical absences to validate current requests that came from outside PeopleSoft, so the longer employees stayed with the organization, the slower it takes to get data imported. Currently, it takes approximately 20 minutes to load 100 absence requests, and the amount of time is gradually increasing while employees accumulate their history. I'd like to