Mark Warburton's men cruised to all three points in front of their home fans, with Clayton Donaldson, Marcello Trotta and Sam Saunders finding the net.
The result allowed the Griffin Park outfit to leapfrog London rivals Orient to the summit, after Russell Slade's side were held to a 1-1 draw by fellow promotion challengers Wolves.
Ethan Ebanks-Landell gave Wolves the lead after five minutes, only for Mathieu Baudry to earn a point for Orient on the hour mark.
Ryan Woods' own goal gave Preston North End a 1-0 win at Shrewsbury Town, but fellow play-off hopefuls Peterborough United slipped to back-to-back losses, as they were beaten 2-1 at Carlisle United.
Louis Dodds and Gavin Tomlin found the net in Port Vale's 2-0 victory over 10-man Rotherham United, who had Claude Davis sent off, while Sheffield United continued their revival under Nigel Clough with a 3-1 win against Tranmere Rovers.
Relegation-threatened Crewe Alexandra came from behind to beat Colchester United 2-1 and earn their first league win in four games, midfielder Chuks Aneke and attacker Tom Hitchcock inspiring the visitors to victory after Luke Garbutt had put Colchester in front.
Former Arsenal midfielder Jay Emmanuel-Thomas netted twice as Bristol City secured their second straight win by hammering Stevenage 4-1.
However, there was no such success for bottom side Notts County, who slipped to a 1-0 defeat at Crawley Town, while Coventry City were held to a 1-1 draw by Oldham Athletic, Bradford City played out a 1-1 stalemate with Swindon Town and Gillingham and Walsall drew 2-2.
