Bug#594245: I found the problem

[alex]

 	All problems (high cpu & slow keyboard response) are caused by 
terminal transparency. When I disable this feature, all works fine again.

 	I can confirm that roxterm has the same problem (disabling 
transparency makes terminal running fast again), so this is not a bug 
related to this packages, but xorg or nvidia closed drivers.

 	Feel free to close this bugreport, I will try to get more info and 
report to relevant packages.