Drop some unnecessary allocations #230
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Putting containers on the heap doesn't do anything since they allocate internally and don't grow on the stack, so it's just additional work having to call into the allocator.
There's only 64 int's which is 256 bytes on most platforms. This improves performance by a small but measureable amount in the tests.
`alphabet += ...` isn't a trivial operation since it has to check if it needs to allocate more memory each time it's called. Since the alphabet can't include any duplicates we can instead create a fixed size buffer and build it on the stack, then perform a single allocation at the end. Also move the storing of the transformed pointers to the end so that the compiler can infer that they don't alias with anything. This gives another small boost in performance.
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These caught my eye so I removed the obvious ones, and then measured the performance to check that it didn't make it worse. I haven't done a thorough check since the scripts in
test_datapoint to files I can't find, so I used the timing tests inrunTeststo check the performance before and after these changes. These results show a decent improvement in some cases.Tests were done by running
runTests 4000 | grep faster3 times and recording the results. Compilers used weregcc 14.2.1andclang 19.1.7. I haven't checked with MSVC but I assume performance won't have worsened.See individual commits for more details.