I am looking to use the computer while the render is taking place. The performance during a render drops drastically (per the users experience) and that is something we need to resolve, however I am not opposed to speeding up the rendering that is in process.
I would not recommend this. Even though the viewport is heavily dependant on the graphics card, 3d programs still use the processor while navigating the viewport. Depending on what renderer you are using, the software will use 100% of the processor cores leaving very little overhead for background applications.
If you absolutely have to render while you work, you can tell the renderer to only use a certain number of cores, which frees up some processing power at the expense of render speed.
From the Max help:
The command-line rendering tool lets you perform batch rendering jobs without having to manipulate parameters by hand in a MAX file. Simple, “one-shot” rendering jobs can be submitted from the Start Run dialog. More elaborate, batched jobs can be rendered through the use of text files; for example, MyRender.bat or MyRender.xml. The ability to edit text files is what provides the power to this tool. You can quickly make changes to your rendering parameters, or output formats, simply by opening your text editor and editing the batch settings.
Command-line rendering is provided by the 3dsmaxcmd.exe program, found in your program install folder.
You can submit command-line rendering jobs that are rendered on a single workstation, or you can take advantage of network rendering and let the Backburner utility manage the jobs across multiple systems.
The Batch Render tool is another way to quickly create BAT files that can be used with the command-line rendering. The Batch Render tool lets you create a queue of camera tasks with specific output parameters, rendering presets or automatic loading of scene states. Once your queue is complete, you can export the tasks to a BAT file that is stored in the \scenes folder.
You can read more about it here ( additional links for flags are in the help):
docs.autodesk.com/3DSMAX/16/ENU/3ds-Max-Help/index.html
