Pdf with Chinese characters renders really slow in Safari

[guoxing]

Link to PDF file (or attach file here):
https://www.dropbox.com/s/l7deqa82azeapg9/safari.pdf?dl=0

Configuration:

• Web browser and its version: Safari Version 9.1.1 (11601.6.17)
• Operating system and its version: OS X 10.11.5
• PDF.js version: 1.4.20
• Is an extension: No

Problem:
Some pdfs with Chinese characters that require specific cmaps (UniGB-UTF16-H and Adobe-GB1-UCS2) to load render really slow in Safari. It takes about 20-30s for a 2-page pdf to finish rendering. And during rendering time it takes the whole CPU power all the time. It works fine on Chrome/Firefox though.

[daveydee33]

This is also very slow in IE11. Roughly 10x slower in IE11 vs Chrome and Firefox.

[AugustePop]

the postMessage from worker takes a lot of time for the font. no idea why. disableWorker somehow alleviate the problem.

[Snuffleupagus]

Given first of all the age of the issue, and secondly the fact that it looks to a platform/browser-specific bug; @timvandermeij does it really make make sense to keep this issue open?