By any means, get a f/2.8 or faster lens. I find myself shooting indoor events more than I though, and my Sigma 24-60 f2.8 is just bright enough at ISO800 or even 1600. I often even grab my 1.4/50 because it's too dark, although a zoom of course is far more usable at this kind of occassions.
AF speed is still okay though far slower than at daylight.
The situation might get a bit better if you have ISO3200 or ISO6400 available, but anyhow you will be happy for every single stop you have in reserve
Don't underestimate one stop - it's half the shutter speed or half the ISO or twice the light ...
The Tamron 28-75 f/2.8 is getting really good reviews, by the way.