The problem is that his implementation is essentially a test of how he's using libc versus how Haskell is using it. The pointer arithmetic he's using shouldn't

The problem is that his implementation is essentially a test of how he's using libc versus how Haskell is using it. The pointer arithmetic he's using shouldn't need to be optimized, since the page sizes he's malloc'ing and pulling from memory are small enough that they should stay in the L1/L2 cache for the entire run(he's using 1k blocks of data, most processors use 4k pages). There's almost no optimization to be done there. The biggest performance hit is actually the single character puts versus a block read or write. Haskell is probably implemented to read a large block of the file(or perhaps the entire file) into memory, then parse after. That would be a minimal number of system fread calls over the entire run. Versus the C code, where 1 block's parse could be 1024 getc and putc calls.