Two new lightbulbs(energy efficient spiral) blink rapidly when I turn OFF the switch for the 3 bulb fixture in my kitchen. House built in 1912ish. My house but previously had tenants. They only had 1 bulb in, so probably occurred for them, too. I'm worried about turning it out now. Wiring internally, probably wasn't updated since 1940's , when house converted to duplex.
Is your light fixture is controlled by a dimmer switch? If so, it might not be capable of properly dimming the more efficient light bulbs.
I had a ceiling light fixture on a dimmer switch. When I changed from incandescent bulbs to LEDs, the light would blink with the switch turned off. Not dimmed, off. I replaced the dimmer with a simple on/off switch and it works as expected now.
I would suspect you have a bad switch. Try replacing it and see if that cures your problem.
The age of your wiring is fine. The lifespan of the insulation on your wiring from the 40's should be good for several more decades if it has seen normal use. Insulation gets degraded from overloading circuits that causes extra heat in the wire. Normal lighting circuits are very lightly loaded. It is the receptacle circuits that would fail first.
There may be enough current from the capacitive coupling in the the wires to allow the bulb to flash. This is more likely with a fixture where the power is fed into the fixture and long wires run off to the switch.
Your best bet may be to try another type of bulb (another brand or LED bulb).
There are better electronic solutions, but the compliance with code may not be acceptable.
Fluorescents are able to be powered by electomagnetic fields... not sure if that is happening here, but it is possible. Tesla actually created fluorescents to be powered without wires. Perhaps some old wiring in the house doesn't have insulation or the insulation is poor; or maybe the house is located near some larger power lines (outside).
Another possibility (if you have an illuminated wall switch): When an illuminated switch is off, the (CFL) bulb is the neutral for the light of the wall switch, causing a tiny current to flow through the CFL bulb. The solution is to solder/install a bleeder resistor to the cfl.