Burning starter to relay cable

I've had this problem for a while and it isn't major but I'd rather not start a fire. My cable from relay to starter likes to get very hot near the relay, and I understand that thing to crank the car for a while might generate a bit of heat, but it's enough that cranking for 5 seconds sometimes causes a poof of smoke from the melting line. One time I even witnessed it melting while the key was in the on position and I had no idea how it did that. I've since replaced the relay and made sure the connection is tight, but this cable keeps wanting to smoke. Any fixes? Or just new cable?

That kind of heat is from excessive resistance. You have to figure it out, or just replace everything. Check corrosion at battery, corrosion at solenoid, corrosion at starter terminal, etc. If those all are good and you cleaned them all, you need to probably replace the solenoid, and/or starter. Sometimes the resistance is internal on one of those. No 'clamp style repaired' battery cables either!
Walt