SpriteBatch:flush
Immediately sends all new and modified sprite data in the batch to the graphics card.

Normally it isn't necessary to call this method as love.graphics.draw(spritebatch, ...) will do it automatically if needed, but explicitly using SpriteBatch:flush gives more control over when the work happens.

If this method is used, it generally shouldn't be called more than once (at most) between love.graphics.draw(spritebatch, ...) calls.
SpriteBatch:flush()