Based on my understanding of your question you are syncing data with SAP on a daily basis. For this, I would give the sync task to a Task Queue and execute it in the background.
In that case, the UI is not slowed down and can perform another action. However, if the data that is synced is critical for the process, you would wait on it. Task Queues can run over multiple threads and nodes. In SAP, you can check if the setting of the task queue is not causing a performance issue.
Another optimization is to only sync the objects that were changed since the last synchronization. For this, you can use various techniques.
To advice better, I should get more details.