Green’s Dictionary of Slang

many, a great quantity, esp. of a desirable commodity.

c.1602		Shakespeare Troilus and Cressida V i: The rotten diseases of the south, the guts-griping [...] loads o’ gravel i’ the back, lethargies.
1783		‘Peter Pindar’ ‘Lyric Odes’ Works (1794) I 55: My Cousin had rump steaks to eat! [...] loads of dainty meat!
1825		J.K. Paulding John Bull in America 290: Their supper consisted of loads of meat, ham, venison, game of various kinds, in quantities sufficient to feast an army.
1856		G.J. Whyte-Melville Kate Coventry (1865) 6: I’ve got bright eyes [...] and loads of soft brown hair.
1861		T. Hughes Tom Brown at Oxford (1880) 52: They might get clever beggars for servitors, and farm them, and so make loads of tin.
1868		H.L. Williams Black-Eyed Beauty 42: Matty had a new dress, ‘loads’ of jewelry.
1900		A.H. Lewis ‘The Garrote’ in Sandburrs 132: There’s dead loads of t’ings about d’ Bend what’s so tough it ’ud make youse sore on yourself to get onto ’em.
1932		‘R. Scully’ Scarlet Pansy 283: Goody, goody, what loads and loads of nice reckless people I’ll meet.
1945		D. Bolster Roll On My Twelve 10: A brilliant Skipper and a damn fine crew, loads of Jerries just asking for it.
1952		C. Harris Death of a Barrow Boy 145: Taxi-loads of ’em. Fleets.
1959		S. Bellow Henderson The Rain King 217: I wish you loads of luck.
1962		K. Williams Diaries 5 Oct. 199: Loads of stories about him making other people pipe down — ‘I told him’ etc.
1991		R. Doyle Van (1998) 499: Best before April ’92. You’ve loads o’ time, wha’.
1996		R. Doyle Woman Who Walked Into Doors 61: She put a mug of tea in front of me. – Loads of sugar in it.
1999		Guardian G2 24 June 17: The Glastonbury Festival was going to be loads of fun.
2000		Guardian Guide 1–6 Jan. 44: Paul [...] makes Channel 4’s day by doing loads of lines during his interview.