Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The OPR file type is primarily associated with 'OPRO X Browser' by OPRO Japan Co.,Ltd..
The OPRO X Browser (OXB) is client software that allows you to view, print and edit, OPR (OPRO Print Report) or OXR (OPRO XML Report) documents that are generated through the OPRO X Server.
The OXB provides various advanced features that cannot be achieved through an ordinary document viewing software.