Unable to play large m2ts videos with additional subtitle file

[Steven_Yang]

The m2ts video(32.~GB) plays well itself(and also with the selectable subtitle inside). However, when I dragged the ass subtitle file into vlc, the screen of vlc got dark and the progressbar went fast to the end.(The video itself is about 2 hrs and the whole "fast forward" process took about 2 mins) It is not the case of the subtitle file because I tried ones made by other translating groups and the mkv(~30GB) converted plays well with all of them.
P.S. I use vlc 64 bit on windows 10
You can use any movies in a BD and any ass subtitles to take a test.

[Jean-Baptiste Kempf]

This is a known issue in VLC. I believe there is already a bugreport on it.

[Jean-Baptiste Kempf]

See https://trac.videolan.org/vlc/ticket/6357

[Steven_Yang]

This is a known issue in VLC. I believe there is already a bugreport on it.

There is no txt file in the same path of the video.
Is there any solution to the problem? If not, where is the source code for this feature located? Maybe I am able to improve it after my final exam.

[Jean-Baptiste Kempf]

This is a known issue in VLC. I believe there is already a bugreport on it.

There is no txt file in the same path of the video.
Is there any solution to the problem? If not, where is the source code for this feature located? Maybe I am able to improve it after my final exam.

in src/input/subtitle.c