My results so far (10 million insertions)

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HashTable, HashTable(1G heap)  : 04.02elapsed, 04.11elapsed
HashTables, HashTables(1G heap): 58.35elapsed, 08.00elapsed
IntMap, IntMap(1G heap)        : 02.88elapsed, 02.64elapsed
Judy, Judy(1G heap)            : 02.07elapsed, 03.00elapsed
Unordered, Unordered(1G heap)  : 23.30elapsed, 15.07elapsed
CPython                        : 04.26elapsed
SmallHash.hs                   : 01.17elapsed (of this, 756ms is for insertions, and 535ms for unboxed int values insertions)
small_hash.c                   : 00.33elapsed