“Cumbersome” is a recognizable word, but it’s, well, a bit cumbersome. The more poetic term for the same concept is “cumbrous” — it’s an adjective to describe something large and unwieldy, or perhaps so complicated that it becomes inefficient. In an obsolete sense of “causing trouble or annoyance,” the word appears in Milton’s “Paradise Lost”: “How I may be quit Fairest and easiest of this combrous charge.”