Yes, if I understand correctly, it should be straightforward to use ApplyThreshold, after LoadImages and ColorToGray/Split. In ApplyThreshold, use the Manual method with a threshold of 0.5, and this should be the fastest method available. In fact, segmentation methods like Identify* or ApplyThreshold are exactly "ConvertImageToObjects" algorithms, just with a different name, so you are correct in your intuition.
Of course, if you could reduce/eliminate the false positives with your original pipeline, then your whole procedure obviously would be markedly more efficient. Feel free to post that pipeline and an example troublesome image and we can perhaps help with that.