Am I doing something wrong?

I have a customfieldlist in an invoice.  I have retrieved the internalid of the Customfield and I want to get the value represented by the internalId.  I've shown a snippet of my code below that gets the value I want, but it goes from 1 minute to 8 minutes processing time by adding the ReadResponse section.  Am I violating some covenant here?

Thanks in advance for any help..

------------------------------------------------------------------------- Record[] records = response.recordList;
Invoice PinnInvoice;
CustomRecordRef myCRR = new CustomRecordRef();
CustomRecord CRR = new CustomRecord();
myCRR.typeId = "2";
    for (int i = 0, j = (response.pageIndex - 1) * response.pageSize; i <  records.Length; i++, j++)
    {
        PinnInvoice = (Invoice)records[i];