In Version 5.0, the Signed Index field on the Advanced tab was set to "Yes" by default; in version 5.1, it is set to "No". If the Vision file has a signed field in the key and Signed Index is set to "No", the entire file will be read, even if the exact key value is sent to AcuODBC. To ensure optimal performance with medium to large files, ensure that the Signed Index field is set to "Yes".