All your tests run (apart from the spawn one but that didn't run to begin with) and we tested it for every single loot pool for 100k seeds, all had the exact same loot, but it is a lot faster.
Benchmarks:
1 item every loot table: same speed
1M items every loot table: 10x speed
1M items only Ruined Portal: 40x speed (it speeds up enchantments a lot)
All your tests run (apart from the spawn one but that didn't run to begin with) and we tested it for every single loot pool for 100k seeds, all had the exact same loot, but it is a lot faster.
Benchmarks: