WebAssembly's Memory64: A Trade-off Between Speed and Memory
2025-01-16
WebAssembly recently introduced Memory64, adding support for 64-bit pointers. Surprisingly, however, Memory64 doesn't result in performance gains; instead, due to limitations in hardware, operating systems, and WebAssembly's design, it can run 10% to over 100% slower than 32-bit mode. This is because 32-bit mode allows browsers to reserve 4GB of memory, eliminating the need for bounds checks. Memory64, however, requires bounds checks, adding computational overhead. Therefore, unless you need more than 4GB of memory, Memory64 isn't the optimal choice. Future improvements in hardware and WebAssembly might improve Memory64's performance.
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