One suggestion is to check if you have other TSM processes running during the backup window. The most power hungry processes are usually the "expire inventory" and "identify duplicate".
Also if your TSM server does not meet the requirements I suggest you move the Operation Center to another server if you have it installed on your TSM server. A VM is good enough for this.
Depending on the platform, check if you have an antivirus that scans TSM related files (database, storage pool, etc) and exclude them if you can, Windows updates schedule, etc
Review the specs of your server and the type of storage pool (file, disk, container), dedup or no dedup, etc, number or clients and see if it meets the requirements.