Hi mhmacleod, and welcome to Intel Software Network, IPP forum.
Please be aware that IPP video library does not utilize any GPU or video acceleration, it is performing completely on the CPU, with a highly optimized performance on Intel processors.
This means that the performance of your H.264 encoding operation is totally based upon your processor (latest Intel processor = Highest performance).
Also, you may try to reduce the processing amount in number of ways; for example, you are setting "Number of B frames between I (or P) " = 3
Well, reducing B frames usage will increase the result video stream size, but also it will reduce the processing load.
Also, the H.264 encoder is threaded with OpenMP*. You need to use the Compiler that can support OpenMP* to compile to threaded code. (Intel C++ Compiler, Microsoft* Visual C++*.NET* 2008, etc).
OpenMP performs the multi threading.
So you need to consider:
1) Encoder threading; check the number of threads used and watch out for limitation.
2) Processor capabilities; Intel new processors powered by Hyper threading (more physical threads per core) and Turbo boost (Load-balancing among processor cores) such as Intel Core i7;
It makes sense, because the encoder is threaded, and it runs within your process (application), the CPU must not be too busy even if the encoders thread is, unless the encoders thread runs with a high priority.
More pixels = more processing. Note that, UMC are just examples, for a complete Intel implementation of video processing, you may consider Intel Media SDK, it is a higher level API, and allows these settings for H.264 encoder (among other components).
The IPP audio-video-codecs samples are contained within a separate IPP samples package ipp-samples_p_6.1.5.060.zip, you may try to locate it within the ISN; also, you may consult an expert from Intel in order to locate the appropriate download link location.
Intel Media SDK forum would be the right place for the media SDK issues and discussions. http://software.intel.com/en-us/forums/intel-media-sdk/