I heard that editing a tuple is a much more expensive operation then editing a list
Are you sure you heard it that way and not the reverse?
Lists have very different performance characteristics depending on which section of the list you edit. Editing in the front is fine. Editing in the back a lot less so, given it’ll invalidate all preceeding cons cells. The values fill be fine, but the refences to the next cell need to be adjusted all the way from the front to the edited element.
