This indicates the proportion of the graphics card memory that is currently used.
This indicator should always remain green.
If it turn RED go to How-to Manage Loading and VRam usage This topic explain how to manage the Loading of the content to avoid full VRAM usage For more information on the GPU Memory Meter Read More for optimizing your show.
Here is a list of tips to reduce the amount of used GPU memory:

1. GPU Memory is shared between all applications, so first, close other applications that may be using the graphics card.
2. Close documents in Smode you don't use
3. Toggle the ON-AIR Enable/Disable ON-AIR mode Read More button twice (this will cleanup unused memory resources)
4. Lower your compo/texture resolutions
5. Reduce the multi-sampling parameters if you used it
6. If nothing else works, simplify your compo and use less images, videos and pre-compositions

See Use optimisation tools to accelerate a composition It is running fast? Could be faster. Read More for more tips on optimization of content in Smode.