Yes, this is related to GPU mining. From cgminer's README:

INTENSITY INFORMATION:

Intensity correlates with the size of work being submitted at any one time to a GPU. The higher the number the larger the size of work. Generally speaking finding an optimal value rather than the highest value is the correct approach as hash rate rises up to a point with higher intensities but above that, the device may be very slow to return responses, or produce errors.

I would just leave it set to 'dynamic,' or --intensity d . That will adjust it automatically depending on how long it takes to complete work.
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