1853510 - Online LZMA compressor is 2x slower in Nightly compared to Chrome

Status: NEW

(Core :: JavaScript Engine, task, P3)

Description

[Mayank Bansal]

Go to http://lzma-js.github.io/LZMA-JS/demos/advanced_demo.html
Copy the sample text in the input.
Set compression level to 9
Click on Compress

Nightly: 70 seconds https://share.firefox.dev/3Lqe1V7
Chrome: 35 seconds

Comment 1

[Mayank Bansal]

Attachment: sample text

Comment 2

[Mayank Bansal]

I tested with different sizes of text, and my observation is that as the input text becomes larger, we progressively get more slower compared to Chrome

Comment 3

[Jan de Mooij [:jandem]]

This spends most of its time in a worker. Looking at the worker's flame graph, this is a poster child for sparse elements.

Comment 4

[Jan de Mooij [:jandem]]

For this and the other sparse element issue you filed a while ago, it'd be interesting to see what the element access pattern is. Question is if these should just be dense or if they're really sparse.