It's either "fixed stuff" for a 3k LoC commit where you moved a bunch of stuff around, or "Added stuff" for a 5k+ LoC commit if you actually added anything new
git ci -am "Addressed performance issue in flurbin module
The flubin module was designed as a successor to the flurbar module
which took in...
[...500 line essay on the hostory, problem and solution deleted...]
Hopefully this will fully fix the issue discussed."
for a one character change that adds an additional, and unrequired, semicolon.