Other supplémental information : I made a test in another Horizon Customer infrastructure that's working on BLAST and when I change to PCOIP, the same latency problem occure. 

Conclusion --> It's not a infrastructure related problem but I confirm that the problem come with the Upgrade from 7.11 to 7.12

To be honest i'm very suprised that there's nothing on google about this ?? I understand that most of people use Blast but not everyone...