Rapper Nas upstages Lauryn Hill in concert

We may never know what Ms. Lauryn Hill is playing at, or whether her demons are, in fact, playing her. Either way, watching her perform is frustrating. She can still sing; she can still rap. Putting on an entertaining show for very forgiving fans, though, is something she either can't do – or won't.

The multitalented Hill belongs in a lineage of African-American musical wunderkinds from Michael Jackson to James Brown to Prince. But where those three had incredibly productive years before going off the rails, Hill had only the Fugees' two discs and a multimillion-selling solo album, 1998's The Miseducation of Lauryn Hill, that cleaned up at the Grammy Awards and gave her the music-industry equivalent of a blank cheque. More than a decade later, Hill has six children, one other release – MTV Unplugged No. 2.0, a strange and depressing live album – and a cloud of speculation that follows her every move, alleging that she is crazy, on drugs, a religious zealot, or all three.

And hey, she might be, but based on her set at the Toronto stop of the hip-hop festival Rock the Bells along with veteran rapper Nas, the jury's still out. She looked perfectly normal, with an afro worthy of Pam Grier and a classy leather skirt and jacket combo, and apologized for being more than an hour late while telling the crowd, "I'm here for you." Hill tore through her lone solo album at cartoonish speeds, however, turning melancholy breakup anthems like Ex-Factor and When It Hurts So Bad into rave-ups and gesticulating at her band with a series of pained expressions and urgent commands.

Even her between-song banter was hurried to the point of being barely comprehensible, and although half of the crowd stuck around to hear her do Fugees hits like Ready Or Not and Killing Me Softly, a steady stream of evacuees swelled to a flood well before she finished, ending with a breakneck cover of Bob Marley's Could You Be Loved. Granted, James Brown was well known for speeding up his songs in performance, but Brown's control-freak nature was always on display. In the few moments where Hill slowed down long enough to hang onto a note, such as when her band cut out behind the "you can't run away" portion of Fu-Gee-La, it was breathtaking how much skill and feeling came through in a split second. Why she refused to tackle a whole song that way is a mystery.

Hill and Nas have a lot in common, even leaving aside their 1996 hit together, If I Ruled the World (Imagine That), which they performed together near the end of Hill's set. In the years since their respective debuts, both felt trapped by fan and record-label expectations, and both have been written off more than once. But their compulsion to pursue their respective muses is hard to dismiss.

For many rap fans, Nas performing his 1994 debut, Illmatic, with producers DJ Premier and Pete Rock and rapper AZ in tow is the equivalent of Bob Dylan doing Blonde on Blonde – the genre's foremost lyrical enigma recreating an album widely acclaimed as among the best ever made. Judging from the audible indifference during much of Nas's artistically bulletproof set, the 1980s babies in attendance hadn't done their homework. The MC dubbed "God's Son" ended on a note the crowd appreciated with relatively more recent hits like a bruising version of 2001's Made You Look. If justice is slow rather than merely AWOL, Nas will be better appreciated in another decade or so. But I'm not waiting to exhale.

Lauryn Hill and Nas