The DTM Buffer Size setting specifies the amount of memory that the Integration Service uses as DTM buffer memory. When you increase the DTM buffer memory, the Integration Service creates more buffer blocks, which improves performance during momentary slowdowns.
Increasing DTM buffer memory allocation generally causes performance to improve initially and then level off. If you do not see a significant increase in performance, DTM buffer memory allocation is not a factor in session performance.
To increase the DTM buffer size, open the session properties and click the Properties tab. Edit the DTM Buffer Size property in the Performance settings. Increase the DTM Buffer Size property by multiples of the buffer block size.