I had this error and it turned out to be models with high poly not sure if this is the case for you but it is for me.
EDIT: your level works ok for me
PC SPECS: Windows 8 Pro 64-bit, Intel I7 (PASSMARK 9529) 4GHz CPU, Asus R9 3GB GPU (PASSMARK 6858) 32GB DDR3 MEM (PASSMARK 2842)