When a task or activity requires a lot of effort and takes a significant amount of time, it can be described as time-consuming. However, there are many other words or phrases that can be used to convey a similar meaning. Some possible synonyms for time-consuming include laborious, arduous, extensive, lengthy, involved, protracted, wearisome, and tedious. Additionally, terms like demanding, strenuous, taxing, and challenging can also imply that a task is not only time-consuming but requires significant mental or physical effort. Using diverse synonyms can not only help to vary sentence structure and improve readability but also add nuanced meaning to writing by conveying detailed information about the nature of the task at hand.