ALLEGRO_VERTEX_CACHE_SIZE man page
ALLEGRO_VERTEX_CACHE_SIZE — Allegro 5 API
#include <allegro5/allegro_primitives.h> #define ALLEGRO_VERTEX_CACHE_SIZE 256
Defines the size of the transformation vertex cache for the software renderer. If you pass less than this many vertices to the primitive rendering functions you will get a speed boost. This also defines the size of the cache vertex buffer, used for the high-level primitives. This corresponds to the maximum number of line segments that will be used to form them.