Yikes, sorry for the slow reply, been busy few days IRL.
How serious are the bug and performance fixes?
Traditionally, I have been open to allowing updates for critical bug fixes. This like crash bugs or 'game starts but you can't play it' or 'game gets stuck on level 2' kind of stuff. The idea being that it doesn't serve anyone to have a broken game in the jam. Plus, I'm a dev too and we've all been there, so I don't think folks can get too upset about bending the rules a bit to help someone out of a crash bug jam.
For smaller bugs and performance stuff, I've generally assumed that players are ok with a few warts considering it's a game jam.