HI Ray,
before you think about Log Partitions I would first check if the bottleneck of the Batch job runtime is really the fact that log inforamtion cannot be written fast engough to the log volume when the transaction is committed. You know that Log is written ansynchronously from the LOG IO Querue to the log volume. The application generally has not to wait until the Log page is written to the log volume. Only if the transaction is committed. Then this commit has to be written as fast as possible to the Log volume and the transaction has to wait until the IO has been done.
This analysis has to be done by SAP liveCache Experts. You could open a customer ticket to get more detailed information about the bottleneck.
Regards, Christiane