Hello, This is an expected behavior for h264 encoder. There are no limitation for evaluation version compare with commercial one. Please pay attention to this article describing legacy policy for this example follow the link: http://software.intel.com/en-us/forums/topic/401253
Another point is, that H.264 codec in UIC is parallelized with OpenMP. Could you try to build it multi-threaded? For that you need to enable OpenMP in h64_enc project.
You are not the first developer who has problem with H264 encoding via UIC.
As it was said previously UIC - deprecated.
But I noticed inside this forum at least one success implementation of H264 encoding via Intel Media SDK.
Media SDK is free of charge now and it has full support of intel.