Recently Shay Shmeltzer blogged how to make JDeveloper faster. I attempted to add a comment on my experience to his blog but received a 403 Forbidden message, so instead I'll post my comment here.
I find at sites with aggressive network virus scanners, the speed of JDeveloper on Windows is hindered by the virus scanner inspecting all the JAR files and other files on your local machine during normal JDeveloper r/w to the filesystem. As you can appreciate a JAR file is a zipped file, so the virus scanner has to unzip the JAR to scan for viruses, which is a double speed whammy (technical term for sloooooow).
From experience a version of McAfee disk-hog was 1 culprit, but luckily you can turn the scanner off for certain types of files (eg. JARs) or subdirectories (eg. the JDev install directory or your project directory).
If the local network monkeys have tied down the virus scanner settings via a magical network configuration, you many need to convince them to turn these settings off for your machine. My advice, just make some reason up that includes your boss's name, the CIO's name, and global warming. I find most network admins think all developers are a threat to network security and you'll need to lie through your teeth to get the exemption.
Don't forget your OAS server too, not just your local machine.
Besides who needs a virus scanner these days? Viruses are so 1990s. These days its all about net-bots, phishing and viagra pyramid schemes ;)