SQL Developer 4.0 and 4.1 have this issue.
I cannot open sql files (text) 180MB and 558Mb in size. I have other files < 127MB that open fine. All of these SQL files were generated by SQL Developer and contain DDL and insert statements.
I adjusted the c:\user\<user>\AppData\Roaming\sqldeveloper\1.0.0.0.0\product.conf file.
AddVMOption -Xms1024m
AddVMOption -Xmx1024m
SQL Developer still wont open the files. Whats up?