One of the strengths of FunnelWeb is that, when writing product files, it does not attempt to evaluate any text expression (e.g. text block, parameter, macro call) in memory and then write the result out. Instead, it always writes out what it is expanding dynamically and directly. This means that the user need not fear defining macros that expand to huge amounts of text and then calling those macros in other macros, or passing those huge macros as parameters to other macros. In all cases, FunnelWeb expands directly to the product file, and there can be no danger in running out of memory during expansion (except for running out of stack space and other marginally used resources in pathological cases).
The only thing to remember in this regard is that FunnelWeb always stores the entire input file and all included files, in their entirety in memory, for the duration of the run.
Here is an example, that illustrates how robust FunnelWeb is:
@! FunnelWeb copes well with the following macro definitions.
@! (Providing that it has a little over ten megabytes of memory).
@O@<woppa.txt@>==@{@<Quote@>@(@<Humungeous@>@)@+@}
@$@<Quote@>@(@1@)==@{"@1"@}
@$@<Humungeous@>==@{@-
...Ten Megabytes of Text...
@}