taxing

requiring much time, effort, or careful attention a very taxing workload that is taking a lot of time to finish Synonyms arduous, burdensome, challenging, exacting, grueling (or gruelling), killing, laborious, onerous, persnickety, demanding, toilsomeRelated Words difficult, formidable, hard, herculean, rough, rugged, stiff, strenuous, testing, tough; oppressive, trying; rigid, rigorous, severe, stern, strict, stringentNear Antonyms easy, effortless, facile, simple, smoothAntonyms light, nondemanding, unchallenging, undemanding