Ruby comparisons benchmark

I recently had to make a huge loop faster (about 10 milllion iterations). The loop spent quite some time checking the state of an object, so I benchmarked some different comparisons in Ruby, on different ruby implementations (Rubinius 2.0.0 pre, MRI 1.9.2-p290 and REE-1.8.7)

Conclusions:

• Comparing symbols is a faster than comparing strings (2.0x~2.5x)
• Integer comparison is even faster (2x in Rubinius, 1.4x in Ruby 1.9.2)
• Using constants that point to integers carries no overhead in 1.9.2, ~25% in ree-1.8.7 and rbx

Between implementations:

• Method calling: Rubinius is ~2x faster than Ruby 1.9.2, who in turn is ~2x faster than ree-1.8.7
• Comparing symbols, integers and integer constants in Rubinius is ~as fast as calling a (boolean) method.
• BUT: defining methods on the fly in Rubinius-2.0.0pre is 2x slower than regular Ruby
• Ruby 1.9.2 has significantly faster comparisons than ree-1.8.7

I might switch from string comparison to symbol (or constant integer) comparison in heavy loops.

NOTE: Benches were run on a 2011 MacBook Pro 2.66 Ghz Core i7.

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