Usage examples for laborious:

• " That's because she is fond of you, too," suggested Gray, thinking of the girl's laborious attempts to teach poor Mandy to dance. "The Power and the Glory" – Grace MacGowan Cooke

• If there came rain, it was even more difficult to keep the fire permanently burning; and, after rain, to reproduce fire was extremely laborious "The White Chief of the Caffres" – A.W. Drayson

• It was evident that he was either endeavouring to remember or to invent, and it seemed rather like the latter and more laborious operation of mind. "Kenelm Chillingly, Complete" – Edward Bulwer-Lytton