sbengine has environment variables for font options:
SB_FONT_HINT="normal"
This corresponds to the default hinting algorithm, optimized for standard gray-level rendering.
SB_FONT_HINT="light"
A lighter hinting algorithm for non-monochrome modes. Many generated glyphs are more fuzzy but better resemble its original shape. A bit like rendering on Mac OS X.
SB_FONT_CACHE_SIZE=[size]
This variable is used to set the size ofthe Freetype font face cache. By default the cache is disabled and a value of 0 will disable the cache. any other number is the number of font faces to cache, using this cache can decrease memory mappings of font files.