When you click (or double click, depending on how Tools > Preferences > Database > Object Viewer > Open Object on Single Click is set) on an object in the navigator tree, SQL Developer has to run the Java code (and initialize the Java class and instance objects) necessary to display what you are requesting. Typically we refer to their UI representation as editors / viewers / browsers. Any initialization delay is not due to database access. To reduce startup overhead, such objects are usually only initialized when needed. So there will be a brief wait when clicking on each object viewer tab for the first time in a SQL Developer session. Opening viewer tabs for another object in the same connection or even an object in a different connection will not require additional overhead, except for the database retrieval time and network delay to access the object.
In addition to initializing Java objects, sometimes an entire application extension must be loaded. For example, when clicking on the Model tab in the object viewer for a table, if this is the first time for a specific install of SQL Developer, then the Modeler extension must be loaded and flagged as something that should be loaded at startup for future sessions. You get a distinct informational popup when an extension is loaded since that takes more time than editor initialization. Actual editor initialization is usually very brief, and the "waiting for editor to initialize" message may be barely noticeable.
The slowest rendering of any tab is typically the SQL tab, to display an object's DDL. That delay is actually due to overhead in the database PL/SQL routines that produce the DDL.
Hope this help.
Thanks Gary, I see this delay for all tabs (Model and SQL are understandable) in browser hence i was asking. Thank you for your explanation, it makes sense now.
This problem exist only on linux.
On Windows platform SQL Dev works well.