Just to report that my first experience with SNAPPY just went south. I have the equivalent of a gpt graph for GRD Calibration + Terrain-Correction implemented in SNAPPY, but it takes 32 mins instead of 6m11 (same box, same GRD file).
java_max_mem: 43G (which seems woefully wasteful for processing a 1 GB zip file).
I like the overall idea of python integration, and would even expect a performance penalty for calling java from python, etc. but 5 times is well beyond reasonable expectation.
My final goal is to do SLC processing, and a 5x penalty in that case would be unworkable. Back to gpt for now, but looking forward to solutions in this space.