*** This run is obsolete. My latest run in this category is here:    • Subnautica Speedrun - Glitchless Hard...  
Subnautica glitchless speedrun on hardcore mode in 1:22:25.

This route skips the search for nickel in the lava zone and gets it by taking the Lost River gate instead. The changes to make this happen lose about 2 minutes total, but it has the advantage of never having to reset due to nickel RNG.