Although I've never shot in a bar, I do shoot bands at church functions, sometimes with special/variable lighting, etc.
The first step is don't go shooting at 5FPS. You've got all night to take your shots, so having to process through 10,000,000 frames is not a good idea. Watch the band for a few minutes and figure out what shots are the best...preferrably not during the really fast music. Figure out, from their music, what kinds of movements/motions are coming in the next 2-3 seconds. Watch the backgrounds, too, to avoid unnecessarily detracting elements (my biggest problem). For me, I like the more 'animated' performers/singers with big expressions, hand/arm movements, etc. But I also try to get about 10 of each performer mostly filling the frame.
I've gone to mostly no-flash photography in those situations. What that means is ISO 3200 or 6400 on my 5D3. Use 8000 if you have to. That way, you should be able to keep shutter speeds in the 1/100th or faster...preferrably closer to 1/250, but that's usually not achieveable unless you are at f2.0 or wider.
I do, however, shoot a couple of flash shots (580EX ii) just as 'insurance', and bounce off the ceiling, etc. The consequences, however, is the colored lights appear almost white. As you're having to deal with CO2, 'tone down' the flash as much as possible with the built in diffuser and/or attached diffuser of some kind...when I have to, I use a generic 'Tupperware' diffuser I found on
ebay.
Next, is your lens. While I love the zoom range on the 24-105 f4L, for that kind of work, it's too slow and therefore doesn't get much use, unless the lights are really bright. So, for fairly-close 'whole band' shots, I use my 16-35 f28L ii. Some from front-on, some angled from the sides, etc. At other times, my 80-200 f2.8L 'magic drainpipe' gets the job done, mostly from the back of the room. And for 'drop dead' thin DOF shots, the 135 f2L...wide open.
Lastly, unless you are under 40 and have rock-steady hands, you'll need some kind of camera support. I use a light weight monopod with an expensive ballhead on top with a quick release clamp as my 5D3 is gripped and has an L bracket on it. I'm fortunate that I don't have to deal with people dancing in the aisles and everywhere else, but when I move from shooting location to shooting location, I have to collapse the monopod before I move.
For what it's worth, since becoming actively involved in my local church, my digital photography has been driven by the need to do low light work without a flash. I finally arrived at a 5D3 and 4 L lenses. In my estimation, I think I've succeded in my quest.