From all that I have read, file-size is a major part of cold-starts as your zip needs to be fetched internally first so there is some app size where increasing

From all that I have read, file-size is a major part of cold-starts as your zip needs to be fetched internally first so there is some app size where increasing the files by pre-parsing might make it slower and only after a certain size would it make sense. Edit: Sorry, you were talking about the runtime, not the app bundle, just realized this now. If it‘s in the runtime it probably is free as that will probably be available in all lambda hosts I guess. Lambda already has an even more aggressive optimization than just pre-parsing, which they call SnapStart; where it takes a RAM snapshot after init and loads that afterwards but I think it‘s inly available in some regions and some runtimes like Java with very slow cold start times.