The Relapse, Olivier Theatre, London

This isn't so much a play as an employment bureau. With 33 parts (played here by 26 actors), The Relapse offers almost as many opportunities for comic distinction, with its conmen, climbers, randy widows and saucy servants, its masquerading, duelling and ravishing. Over three-and-a-half hours, however, this play of 1696 shows that, pace Mae West, too much of a good thing can be indigestible.

The directors Trevor Nunn and Stephen Rayne started out with a handicap in the form of the Olivier Theatre, which nearly always seems too big for whatever is performed in it, and is especially outsize for this frothy, gossipy play. The designer Sue Blane boldly cuts it down, though, by building her own scrumptious red-and-gold playhouse on it, with boxes for fashionable couples to guffaw at Vanbrugh's still-fresh jokes. Told that he can't join the army because he's a Jacobite, a young man replies: "Thou may'st as well say I can't take orders because I'm an atheist."

The costumes are a hoot, too: decked out for his wedding, Lord Foppington looks like the cake, and in his country-visiting outfit he resembles a one-man garden party. He is especially overdressed for calling at a castle crammed with yokels who pop up like jacks in the box to let off antique firearms, shake their fists and gibber. If the country is a hotbed of imbecility, London pullulates with vice.

The title refers to Mr Loveless's return, after a period of marital fidelity, to his skirt-chasing ways. While he pursues his wife's cousin (the vivacious Claire Price), another gallant woos his neglected wife. Meanwhile, the lord's penniless younger brother Tom (a rather prissy Raymond Coulthard) impersonates Foppington, who has arranged a marriage to a bumpkin heiress.

But while forgoing sentiment, Vanbrugh doesn't take his cynicism far enough – nothing really bad happens to anyone. The lack of threat, the shunting between parallel plots, the over-extended comedy and our indifference to the fate of all these unsympathetic characters create a very over-egged pudding.

James Purefoy is a lacklustre Loveless, while Imogen Stubbs is full of stale girlish mannerisms as his wife. But Adrian Lukis is a mesmerically purring seducer, James Hayes a drolly impertinent flunky and Janine Duvitski a cosily naughty nurse. The play, however, belongs to Alex Jennings's Foppington, a drawling monument of camp ("My life is a perpetual stream of pleasure") who, swooning at his powdered and painted reflection, puts one in mind of Edith Sitwell blissfully entangled with Cyril Ritchard.

The most screaming performance, though, is that of Edward Petherbridge in the small part of the homosexual matchmaker. I won't spoil his best bit of business, which had the house roaring and groaning in its emphatic comment on 17th-century hygiene.

Booking to 15 September (020-7452 3000)