The following environment variables can be set to influence the behaviour of Open Inventor:

IV_SEPARATOR_MAX_CACHES	Set the default number of render caches on SoSeparator
IV_NO_VERTEX_ARRAY	if set, turns off vertex array rendering and uses deprecated immediate mode rendering
IV_NO_VBO	if set, no VBOs are used (but vertex array rendering will still be used)
IV_NO_NPOT	if set, no non-power-of-two textures are used by SoTexture2

These additional enviroment variables can be used in the debug version:

IV_DEBUG_CACHES	debug info on the cache usage
IV_DEBUG_CACHELIST	debug info on the cache list
IV_DEBUG_MATRIX_CULL	debug info on matrix culling
IV_DEBUG_RENDER_CULL	prints infos on culling while rendering
IV_DEBUG_PICK_CULL	prints infos on culling while picking
IV_DEBUG_SENSORS	prints infos on sensors
IV_DEBUG_TRANSFORM_MANIP_FIELDS	prints infos on transform manipulator fields
IV_DEBUG_WRITE_KIT_CHILDREN	prints infos when writing kit children
IV_DEBUG_KIT_PARTS	prints infos on kit parts

These additional (MeVis only) enviroment variables can be used in the debug version:

IV_DEBUG_VBO_RENDERING	prints infos when VBO rendering is used
IV_DEBUG_LEGACY_RENDERING	prints when legacy immediate mode rendering is used instead of Vertex Array rendering