# Database Discussions > IBM DB2 >  CPU overhead when using Declared Global Temporary tables on DB2 version 10 on z/OS

## hnipen

Hello all

I am in a project where we do have some urgent issues coming from the fact that using Declared Global Temporary Tables (DGTT) uses excessive CPU, this is with a service that is hi-load and that will be called in parallel up to 13 times per second. Technically, we have to use temporary tables.
It is our understanding that most of the overhead is coming from the required CPU- work to create and drop the table in the buffer pool/workfiles and logging (v10 does not have the not-logged option).
The functionality I am talking about here is within a stored procedure.

The same function as described above utilizing Created Global Temporary Tables (CGTT) shows significantly less CPU overhead, about 1/3 of the CPU utilization of using DGTT.

My question is simply as follows:
Are there any good tips on how to significantly reduce CPU processing when using Declared Global Temporary Tables?

Constraint:
We just do not have the necessary time now to change from using DGTT to CGTT as this requires quite a lot of development effort, we dont have the time and the reprogramming is a risk we cannot afford at this stage.

*The simple goal that we have to meet is to significantly reduce CPU utilization, there are no performance issues.*

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