I wonder if your forestay and or back stay are too loose. The forestay should have a bit of curvature when under load (ie going to windward) but not too much, and there should be no slop or 'wiggling and jiggling' for lack of a better term.

I only put modest tension on my cruising jib halyards, enough to keep any scalloping out of the luff. Definitely not a heavy crank on the winch. They aren't racing sails that need to have the draft pulled forward by tensioning.

I wonder if your halyard is taking some of the load that should be borne by the rig.

Just a WAG, it's hard to make a judgement without seeing it, but that would be my first thing to ask.