Parsing source maps is a significant performance bottleneck for the devtools. The parser implementation is written in JS and is already optimized to the point where we don't expect to get any big wins there. The only way to get better performance at this point would be to rewrite the parser in either C++ or asm.js. Since the source-map library is used by people outside of Mozilla as well, asm.js seems the best option here.
Rust is the new hotness. https://github.com/tromey/vlq Though it seems to me that this is less important now that the decoding is done in a worker. Marking it P4, the forgotten P.
Priority: -- → P4
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