Interesting, is there any chance that you are overriding the (parse object name $ as $ $ $) in your source code, but forgot a (just) in there so that the execution falls into the library version as well? That rule is queried as multi, so that would possibly double the heap usage in one fell swoop.
If you are willing to share your code with me, you can send it to me in a DM and I would take a look. Other than that, I am afraid that’s all that comes to my mind for shooting in the dark.