ID 483550 - Poor playback performance of h264 files at x2 speed, compared to other codecs

Problem summary
Poor playback performance of h264 files at x2 speed, compared to other codecs.
This behaviour has been reproduced on Windows and CentOS 7, with files that are being read from a local drive.

Customer reported version
N/A

Customer reported platform
Linux

Steps to reproduce

1) Open Nuke Studio.

2) Import (File > Import File(s)...) the attached h264 file.

3) Double-click the clip in the Bin to open it in the Viewer.

4) Play the clip at x2 speed (press L key after press the play button in the Viewer) and notice the fps indicated in the Viewer.

5) Repeat steps 2-4, with the attached DNxHD file. While there may still be some drops in fps, the performance should still be better than the h264 file.

Expected behaviour
h264 files should achieve similar playback performance to other MOV codecs

Actual behaviour
The playback performance of h264 files is poor at x2 speed, compared to other codecs

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
Nuke Studio 13.0v3 - Windows 10 - Linux CentOS 7
Nuke Studio 12.0v1 - Windows 10
Nuke Studio 11.0v1 - Windows 10
Nuke Studio 10.0v1 - Windows 10
Nuke Studio 9.0v1 - Windows 10

Unable to reproduce bug in:
Nuke Studio 13.0v3 - macOS 10.15 (Catalina)

Earliest version tested
Nuke Studio 9.0v1
- This issue appears to be in all versions of the product