Why is JSON faster than BSON in node.js?

Question

After reading this, there is a quote that stood out:

BSON is also designed to be fast to encode and decode. For example, integers are stored as 32 (or

Answer 1

The question should not be Why is JSON faster than BSON? but Why is JSON faster than BSON in node.js?.

In most environments binary encodings like BSON, MessagePack or CBOR would be easier to encode than the textual JSON encoding. However javascript environments (like v8/node.js) are heavily optimized for JSON handling (because it's a subset of javascript). JSON de/encoding is probably implemented there in native code in optimized fashion directly in the JS VM. The javascript VMs are however not that optimized for representing and manipulating byte arrays (which is used by a BSON library). Nodes native Buffer type might be better than a pure JS array, but working with it (and doing for example the JS string (UTF16) -> UTF8 byte decoding in JS) is still slower then the inbuilt JSON serialization.

In other languages like C++ with direct byte array access and utf8 string types the results might be completely different.