How do optimise the performance of Remmina?
AFAIK Remmina uses FreeRDP as its RDP backend. Since FreeRDP is under heavy development the FreeRDP version (0.8.2-2build1) in 11.10 may not be as optimized as the development versions from the FreeRDP homepage.
For high-performance (kind of) RDP connections to Windows 7 (or other RDP servers) I use rdesktop (command line) with the following settings:
rdesktop -a 16 -z -x m -P SERVERNAME