If the E5's embedded 8051 isn't fast enough to implemented some key section of code, it may be possible to offload some of the algorithm into the E5's embedded programmable logic.

In one example, I had a customer that needed to quickly calculate Ax+B to 24-bit resolution. We helped create the logic so that the 8051 was basically only moving data. The heavy lifting was done in programmable logic.

For some other ideas on the subject, please take a look at the following link. It's from the pre-Triscend days but is still applicable, even using the E5.

"Programmable logic overcomes processor bottlenecks", Personal Engineering, March 1998, pp. 48-53.
http://www.optimagic.com/acrobat/pein_0398.pdf

You also had a question on where you might learn about CPLDs, etc. I'd like to recommend another web site.

The Programmable Logic Jump Station
http://www.optimagic.com

In specific, there is a now-outdated but still useful FAQ. Plus, there's a section where you can download the free versions of software from various CPLD vendors. Fortunately, most CPLDs are supported in the free versions.