Hi @Eliott_Audry, I am so sorry for this. I tried manually running your workflow and was indeed able to see my memory consumption creeping up continuously stronger than expected, even when not using queue mode. I suspect this could be related to the Code node. Can you try adding a Set node at the end of your sub-workflow and verify if this reduces the memory consumption for you?
Something like this:
I am currently on iteration 328 with the memory usage being fairly consistent at around 480 MB:
