Note : HDMI sound speed increased in Ubuntu 14.04 - Kernel 3.11 with Intel Haswell

On a Intel Haswell Chipset, the problem of HDMI sound speed is solved by forcing the audio driver not to go in power-save mode. I don’t know however if this trick create some power consumptions issues…
This is the only solution that worked for me. Neither editing pulse-audio or intel-audio-dma files worked.

Here is to solve it :
Open Grub file :
sudo gedit /etc/default/grub

Edit Grub line. Change :

To :
GRUB_CMDLINE_LINUX_DEFAULT="i915.disable_power_well=0 quiet splash"

Save file & close text editor.
Run :
sudo update-grub

Wait for command to finish, then reboot computer.

Bug solved for me.