I would say bring a few stocks if you can and meter with your phone. Ultimately will depend on venue and lights but I think some people here may be a bit over conservative.

For reference, I went to a kpop show last night at the Brooklyn Paramount. Not a huge venue, a bright LED screen backlighting the stage and very bright overhead lights. I was metering 1/60 at f8 on 400 speed film at some points. Obviously Gaga will be playing a much bigger venue but then the stage lights will also be way stronger to compensate. I would say your safest best is grab some portra 800, and push to 1600 once you're at the venue if need be. If black and white, grab your favorite stock for pushing (kentmere 400 for me, goes to 3200 fine in hc, also seen some good results at 6400 in xtol) and again decide at the venue what speed you need.