The Instance Duplicate Maps utility searches an entire scene for materials that have duplicate Bitmap maps and give you the option to instance them. If your scene has different materials that use the same texture maps, creating instances will reduce the load on your video card, which can improve viewport performance.
For example, if you render a scene containing three materials that reference the texture map MyMap.bmp, 3ds Max searches for that texture map three times: once for each material it is used in. However, if you use the Instance Duplicate Maps utility, you can create instances of the duplicate maps so the renderer will find the first reference to MyMap.bmp and use it for any subsequent material that uses the same maps.
This utility searches an entire scene. You do not need to select objects or materials.
Animation is not supported as a criterion for determining duplication, so any differences in the animation of Bitmap map parameters will be lost from the use of this utility. For example, if two materials use the same bitmap image applied as Diffuse maps, and have the same initial Tiling settings, but their Tiling settings are animated to different subsequent values, after using the utility both maps will have the same animation as the first map.
To instance all duplicate maps:
The Instance Duplicate Maps dialog opens, displaying the following:
The dialog displays a list of all texture maps found to have exact duplicates in the scene. The search will include all copies found to have identical paths and settings.
To instance only specific maps:
Perhaps you only want to instance a few of the texture maps found in specific materials.
The Instance Duplicate Maps dialog opens.
If you don't select at least two entries, you will see a warning in the status field at the top of the dialog.
Since all three of the maps were instanced, the dialog now shows there are 42 duplicated textures.
The primary user interface of the Instance Duplicate Maps utility is the Instance Duplicate Maps dialog, which you open from the Utilities menu in the Material Editor. This utility works globally, so you do not need to select objects or materials in order to use it.
The dialog consists of three parts: a status field at the top, a drop menu containing duplicated texture maps and a list of map names and the materials that belong to.
The Status Field is not interactive. It shows you prompts and warnings about the duplicate textures and maps. Some of the messages displayed in this section include:
This drop-down list contains all the maps in the scene found to be identical in every way, including texture map path and name, and initial parameter settings. The number after “Duplicated Textures” indicates how many sets were found in the scene. This list appears with the first entry visible and once active can be scrolled using the up/down arrow keys.
When you choose a texture in the Duplicated Textures list, 3ds Max displays its duplicates in the Duplicates list, showing the map name and the name of the parent material. The number after “Duplicates” indicates how many copies were found in the scene. Textures in this list can be chosen individually. Only duplicates chosen in this list will be consolidated into the final instance if you click the Instance button. The name of the resulting instance is that of the first chosen duplicate in the list.
Compact Material Editor 
Utilities panel