ANNOUNCEMENT: community.oracle.com is currently Read only due to planned upgrade until 28-Sep-2020 9:30 AM Pacific Time. Any changes made during Read only mode will be lost and will need to be re-entered when the application is back read/write.
In R4 EA, response time is reasonable at first. After working in SQL Developer for a period of time (opening and closing large objects, editing, et cetera), I find the tool slowing down drastically. Killing it (via Windows Task Manager) and restarting it gives me faster response time.
A similar problem exists in version 3.2, albeit it manifests more quickly in R4 EA.