Issue with numerous items selection !IMPORTANT and CRITICAL for ME!

The issue is about WindChill RV&S ver. 12.... I have critical problem with selecting and processing more than around 50 items from over 1000 items heap. This is very bad situation because what should have taken me 1 minute took me 2 hours!. I cannot send you screens about details but ERROR msg MKS134744 was returned when more than 50 items were selected. Please try to answer the details how to fix it for the future job. Because nobody is willing to pay 120 times more for my job (one minute vs 120min). Thank you very much for your understanding.