Hello! I’ve committed a fix that allows fluid numbers to be recycled, which in turn leads to smaller fluid vectors in dynamic states:
http://git.sv.gnu.org/cgit/guile.git/commit/?id=bd5a75dcd8436ebe077c9ce52300d013e9519d94 There’s still room for improvement, see ‘TODO’ in ‘fluids.c’. Thanks, Ludo’.