This options will increase the performance of your JDeveloper under 64bit systems with 4 or more GB or RAM.
First locate the file jdev.conf (on my system is C:\Oracle\Middleware\jdeveloper\jdev\bin\jdev.conf) and add this values:
#Extra tunning options
AddVMOption -XX:+AggressiveOpts
AddVMOption -XX:+UseStringCache
AddVMOption -XX:+OptimizeStringConcat
AddVMOption -XX:+ScavengeBeforeFullGC
AddVMOption -XX:+UseCompressedOops
AddVMOption -XX:+UseConcMarkSweepGC
AddVMOption -XX:+UseGCOverheadLimit
AddVMOption -XX:MaxPermSize=800M
After that configure your JVM to use more memory
Under directory C:\Oracle\dev_home\system11.1.1.5.37.60.13\DefaultDomain\bin (or similar) the file setDomainEnv.bat (this only applies to 64 bit)
set XMS_SUN_64BIT=256
set XMS_SUN_32BIT=256
set XMX_SUN_64BIT=1024
set XMX_SUN_32BIT=512
Thats all, now your JDeveloper should be a bit faster
:-)