first request of range request download whole pdf file？

[yuweiming2016]

Configuration:

• Web browser and its version: chrome 75
• Operating system and its version: centos7.3
• PDF.js version: 2.1.266
• Is a browser extension: no

I opened the pdf.js demo with chrome and I found that the range request was in effect, but why did the first request download the whole pdf file?

What is the expected behavior? (add screenshot)
i expect result as follow:

Am I missing something?

http://mozilla.github.io/pdf.js/web/viewer.html

[Snuffleupagus]

This is the expected result of PR #8768, which was needed to address issue #5319. Although it's not recommended to disable streaming for performance reasons, it can be done using the following option:

pdf.js/src/display/api.js

Lines 189 to 191 in 7af66c8

	* @property {boolean} disableStream - (optional) Disable streaming of PDF file
	* data. By default PDF.js attempts to load PDFs in chunks.
	* The default value is `false`.

[yuweiming2016]

@Snuffleupagus, thank you for you answer! it work for me now. may i ask why there is some performance reasons when settting disableStream=true？