thank you for your forum post and sorry that you have encountered a problem.
I am not aware of any specific performance problems. If you added a schema that is very complex, would expect Source Control for Oracle (SCO) to take a longer time to refresh compared to schema containing much fewer objects.
Also you need to take into account the workload of the Oracle server, TFS server, the machine running SCO, network bandwith.
There are no configuration settings within SCO that will speed up the actual refresh process.