This is in the operations, specification of the capabilities of the plugin and properties. Connections between plugins are extremely light-weight. Data can travel the pipeline with minimal overhead. Provide a mechanism to directly work on the target memory. A plugin can for example directly write to the X servers shared mem.
Buffers can also point to arbitrary memory like kernel memory.
Refcounting and copy on write to minimize the amount of memcpy. Subbufers to efficiently split the data in a buffer. Pipelines can be constructed using cothreads to minimize the threading overhead. Cothreads are a simple user-space method for switching between subtasks. HW acceleration is possible by writing a specialized plugin.