This raises many good questions; however, at this stage, answering most would require crystal ball gazing.

In terms of memory vs. speed; the latter is, by far, the more important.

Choosing the largest file (/usr/share/dict/australian-english) for testing, then finding the encoding requirements (details earlier) was probably fortuitous in that it alerted me to this issue. However, strings containing sequences of A, C, G & T have only 7-bit ASCII characters and would not require encoding. Testing with /usr/share/dict/linux.words may have interesting results.

Although I did see potential $work applications, this really just started out of interest and was an academic exercise. I'll probably still continue investigating the aspects mentioned earlier, even if unsuitable for $work.