When opening a file or pasting from a text file with a large amount of insert statements (approx 3000), the editor takes about 10mins before you can start working with the file. At this point the CPU is also at 85%. Opening the same file in Toad 10.5 has no issues.
WORKAROUND
Toad 10.5 can be used to load the file
STATUS
Waiting for fix in a future release of Toad for Oracle