On 07/05/2015 04:51 AM, Liam O'Toole wrote: > One practical difference I have seen is the improved performance of -Y > over -X. I have long attributed that to the relaxation of security > controls in the former case. When and how did you measure that? The -Y change was introduced in Fedora Core 3, in November 2004. The default was changed to ForwardX11Trusted=yes just a month or two later. I'm not sure -X and -Y ever behaved differently on Enterprise Linux or CentOS. At this point, I don't think it's even possible to set ForwardX11Trusted=no any more. The X SECURITY extension was replaced with "X Access Control Extension" several years ago.