I think they look alike because inside the high coherence areas you already have very good phase quality, so the effect of Goldstein filter is only minor.
The duration of graphs often depends on the current cache. It can be completely different once you close SNAP, restart and only load the input product.
As you are already working with graphs, try the command line with gpt, which was reported to be significantly faster: Snaphu export / import take a very long time