I have been wrestling with most of the various stuttering, freezing, hic-cups just before touchdown, etc. for 2 years. Since the release of SU10 I think I have managed to tame this sim to the point where it is actually very stable, smooth and predictable.
Keeping in mind that my goals, unlike many, is not to achieve high FPS but rather to have solid, non-jittery flights, I have shared my settings and system specs in another related thread. You might want to try them and see if they eliminate your touchdown issues.
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