1646265 - download speed very slow if blob size greater than 1MB

Status: UNCONFIRMED

(Core :: DOM: Core & HTML, defect)

Description

[yrj0103]

Attachment: sample.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36

Steps to reproduce:

1. Create a blob from an array of Uint8Array (length of array is greater than 100000)
2. Use URL.createObjectURL(blob) to create URL
3. Use HTMLAnchorElement to download the URL

see sample.png

Actual results:

Download speed is very slow after 1MB

Expected results:

Complete download immediately

However, if I concat those Uint8Array to one Uint8Array before creating Blob, it would complete immediately as I expected.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

Reporter, could you perhaps attach a minimal testcase using 'Attach new file'?

Comment 3

[yrj0103]

Attachment: download.js

Comment 4

[Henri Sivonen (:hsivonen)]

I see a bit of a wait, but maybe I'm using a computer that's too fast.

Comment 5

[yrj0103]

Attachment: 2020-06-18 170523.png

Download speed is less than 1kB/s

Comment 6

[Olli Pettay [:smaug][[e-mail]]]

Attachment: testcase