Problem Uploading Large GL65 Files

Hi All;

  We are on the Iseries (AS/400) using Lawson v 9.0.0.9, Lawson Addins 9.0.3.  When 2 or 3 users try to upload a GL65 File simultaneously using Addins and the file has between  3,000  - 4,500 rows, Lawson comes to a crawl.  One time, I had to shut down everything and restart Websphere. The users are using MS Excel 2007 and 2010.    At the moment am having them upload large files 1 at a time. Would appreciate any recommendation on enhancing the performance of the tool.   

Jean