It’s only three years old this year, a flea on a continuum the size of your dog (the Europeans, after all, have been at it for billions of centuries). But the Seaport Village Spring Busker Festival has gained such a rep for its grass-roots entertainment value that the brass had no choice but to add a nightly performance slate this time. Buskers After Dark, which will feature a DJ guest appearance, is designed to complement the daytime entries, featuring an array of street-performing sword-swallowers, stilt-walkers, jugglers, acrobats, comedians and musicians. And again this year, the public gets to vote for its favorite three performers, who will earn prizes courtesy of the Manchester Grand Hyatt Hotel. And don’t forget the food and stuff. The fun takes place Saturday and Sunday, April 18 and 19, from noon to 5 p.m., with the nighttime edition running April 18 from 7 to 10 p.m. Seaport Village is located at West Harbor Drive and Pacific Highway, adjacent to Embarcadero Park North. Visitors receive two hours of free validated parking with any purchase. For more information, go to seaportvillage.com or call (619) 235-4014.