Hi,
We recently bought a new machine with like 4 GHz processor, 16 GB of RAM. For the graphic card, we use the Radeon R7 250 1000 MHz GDDR5.
Latest version of Ubuntu (14.04 LTS) was installed along with GNU Radio built from the source. Everything seems to be installed just fine. However, when trying to use GNU Radio Companion (GRC), the GUI's are so slow. Every time I try to place in or move the blocks in GRC, the whole GUI stuck for a while and it gets so slow. Because of this, I am not able to run GRC.
Prior to this, GRC used to work just fine on another machine with a much lower specs for the RAM and the processor but with RS880 [Radeon HD 4200] graphic card.