I have an house built in 1949 with some gnarly things going on in the wiring. I have pretty good handle of everything that runs off the main panel, but the subpanel I just thoroughly investigated. One circuit is of primary concern right now.
It has on it:
Laundry room outlets
Laundry room lights
Boiler room outlets
Hall light
coat closet light
spare bedroom light
spare bedroom closet light
spare bedroom outlets
Bathroom outlets
Bathroom light
Bathroom fan
Master bed outlets
I was able to trace boiler room and laundry room wiring, but then it gets over the finished basement bathroom (which they also tied into a circuit from the fuse subpanel with old wiring, instead of taking the extra hour and 40 feet of romex to go to the main panel through the unfinished portion of the basement!!). So I lose it there.
Ideally I want to tear out everything except the first three items on the list (which are in the basement) and run romex to the main panel. To do that, at a minimum I would need to remove some of the finished ceiling in the basement bathroom, and some of the drywall in the other finished part of the basement. I'm skeptical that will be all the demo needed.
Alternatively, I am thinking I just disconnect from the last junction box before it goes upstairs, and abandon the wiring in place. It's relatively easy to run a line into the attic from the main panel, but I'm not sure how easy it will be to drop all the lines I need to from the attic to the outlets. In fact, the demo sounds easier the more I think about it.
What is your concern?
My first reaction is yes, it seem that there is too much stuff on the circuit. . . At least by what modern code would likely dictate.
That being said, technically overloaded is not inherently unsafe. If wired correctly, the wire is in good condition, and the breaker/fuse is correctly sized to the smallest gauge of wire in the circuit, the worst thing that will happen is you blow the breaker/fuse. This can be mitigated by switching the lights to LED (good idea anyways, especially if there is a state incentive/discount).
Personally if you are not routinely tripping the circuit breaker/fuse on that circuit and there is no indication that is otherwise dangerous I would be tempted to leave it alone for now. After all if everything else is done right it should be safe and it is currently causing you no inconvenience and presumably hasn't been a problem going back as far as it has been in its current configuration. Of course if you had another project that required most of the demo work (adding a new circuit for example) I would bring it up to modern standards (or at least closer to modern code as possible.)
Now if the wiring is undersized, over fused, knob and tube with romex questionably tied in, missing isolation, suspected of concealed junction boxes, it would move up my priority list.
Older houses often have wiring that has grown "organically" and by that I mean someone has add one or two things here or there and simply tapped into an existing circuit.