UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36

Example URL:
http://60.205.145.196/download/test.html

Steps to reproduce the problem:
1. open http://60.205.145.196/download/test.html
2. click on the second upload file button(beside with  "with filter")
3. notice the open file dialog shows up very slow with a large!

What is the expected behavior?
the open file dialog shows up quickly.
Please check the first upload file button, which can show up quickly.

What went wrong?
It shows up with a large latency.

Does it occur on multiple sites: Yes

Is it a problem with a plugin? No 

Did this work before? Yes Not sure, but in some old version.

Does this work in other browsers? Yes 

Chrome version: 53.0.2785.116  Channel: stable
OS Version: OS X 10.12.0
Flash Version: Shockwave Flash 23.0 r0

Please help fix it asap!