On the recommendation of a gardener with feijoa fruit bigger than my hand, I have pruned my feijoa back to stumps.
The theory is that the fruit was beyond useless as the tree stood, being as there was masses of them, but none grew larger than a marble. So I've lost nothing if it dies right off.
If it doesn't grow back and fruit better, I'm never listening to her again and will be investing in a new plant. Right along with a Black Doris plum, which we had access to via a huge branch from the neighbours. But they cut it down - apparently I had the only healthy branch.
Yes my brother had a feijoa hedge and the harder he pruned the bigger the fruit got so that's what we have done with ours.
