Methods, systems, and computer-storage media fare provided for utilizing a GPU for user-defined image compositing operations. A sequence of compositing operations is determined for a graphical image document based on at least one user-defined layer property such as a layer mode or an opacity level. A domain-specific language runtime, such as Halide runtime, is used to provide encoded objects for each operation within the sequence with the code being optimized for the GPU platform. A command buffer with a plurality of commands comprising the encoded operations is created and committed to the GPU for execution of the compositing operations. Commands are committed to the GPU in an asynchronous nature such that additional command buffers may be created and committed the GPU prior to receiving a response from the GPU on an earlier command buffer.