The man in the Slim Goodbody bodysuit and matador cape who kicked off the concert by introducing frontman Kevin Barnes should have tipped us off. By the time the man in the Flash costume and giant Abraham Lincoln head paraded an American flag around dancers in voluptuous, flesh-colored bodysuits and evil-poodle masks, it was clear: Of Montreal is unlike most acts that grace the stage at Port City Music Hall. This was a good, old-fashioned freak-out, as Homer Simpson might say, and a deeply satisfying set of crowd-pleasers from throughout their catalog.

Of Montreal is one of the most vital bands of the past 20 years, beginning as a Beatles-esque indie-pop in the 1990s before morphing into a glam-funk band with the occasional art-rock outbursts in the mid-2000s, and then veering into everything from straightforward R&B to avant-garde instrumental compositions to Dylan-esque folk-pop. They lace their robust compositions with hyper-emotional, slightly bratty lyrics, and put out a reliably solid album of such music every couple of years.

It all blends into a psychedelic wash in concert, splintered shards of guitar squalls and brittle funk riffs, boogie-woogie drums, bass grooves as round and smooth as marbles, all making such hairpin turns that it was difficult to keep up. They’d slip in surprises, such as melting the first verse of Joni Mitchell’s “The Last Time I Saw Richard” into their own “Obsidian Currents,” or showcase different aspects of more recent songs, such as the gear shifts of “Empyrean Abattoir.” With about six songs to go, they uncorked the dance party portion of the set, hopping to irresistible keyboard riffs and bouncing bass in funk songs such as the “The Party’s Crashing Us” and “Gronlandic Edit.”

These songs came from the middle portion of their career, when their popularity crested with albums such as “Sunlandic Twins,” “Hissing Fauna, Are You the Destroyer?” and “Skeletal Lamping,” a string of releases that explored manic depression and pan-sexual escapades with equal aplomb and to ever-increasing audiences. Their stage shows at the time reflected the over-dramatic nature of the music, complete with costumes, catwalks, and one time, memorably, a live horse. They’ve dialed that back to a degree, but remain in constant search of ways to give the audience more than just five dudes standing on stage. In addition to the dancers in elaborate costumes, the band performed in a bath of kaleidoscopic light, with colorful images projected precisely on white sheets.

For such an electric and imaginative set, the crowd could have been bigger. Blame the late-night Wednesday set time, or the fact that the band has ignored this market for too long – it’s always hard to tell. In the 1990s, Of Montreal was one of many bands in the psychedelic indie-pop collective Elephant 6. Jeff Mangum’s Neutral Milk Hotel, another band in this collective, released two albums – one great, one good – and hasn’t released anything else since 1998. Upon recently resurfacing, they’ve sold out the State Theatre twice in three years. Of Montreal, meanwhile, has given us two decades of music – a lot of it great, a lot of it good – and in 2015 struggles to fill Port City Music Hall, a much smaller venue. Sometimes, vitality and restless creativity simply don’t pay.