JDeveloper 11.1.2, Windows7, 64bit
Unable to load performance pack. Using Java I/O instead. Please ensure that wlntio.dll is in blah....
I get this error message on my local windows machine and it annoys the hell out of me so I had to fix it.
Step 1) Download the generic install version of Jdev (jar version)
Step 2) Install this with a 64 bit vm -- cmd prompt java -server -jar jdevstudio11115install.jar (I used the -server parameter I dont know if this makes a difference but I dont feel like trying without it.)
Step 3 ) make sure you use a 64bit jvm in the install
Worked for me.