Can you describe your issue a bit more detailed:
- What version of Oracle are you using?
- How many objects do you have for each object type(roughly, tables, indexes, views, synonyms etc.)?
- Have you gathered dictionary statistics?

What is causing the delay? A lot of the queries used to populate the Object Window (I assume you mean the "Schema Browser" by "Object Window") are still using the "RULE" hint. This might cause suboptimal performance in the recent Oracle releases like 10g or 11g.

It would be interesting to know more details, because e.g. if the query itself is slow any additional filtering performed afterwards won't actually speed up the process. It might become faster if we add more filter criteria to the query, but I think that the application in general should actually be capable of handling several thousand objects per type without any issues.