AUSTIN, TX — Although the 60 Nexus 4 x 4 panels from Chauvet Professional used by LD Cory Fitzgerald added dramatic visual effects to Lady Gaga’s SXSW performance here last month, the fixture’s compact size and easily linkable hardware helped keep the drama backstage to a minimum — which was a good thing, considering that the design team and crew were already faced with a stressful change of venue for the artist’s performance.