Sure everything was more expensive, but not by the same factor. Main memory was smaller but also relatively faster compared to CPU. Search for "386 simm memor

Sure everything was more expensive, but not by the same factor. Main memory was smaller but also relatively faster compared to CPU. Search for "386 simm memory" and you'll see 60ns modules. Considering that 386 debuted with 12MHz clock, 60 ns is faster than one CPU clock cycle! In other words, "reading the whole string from memory" could be a performance problem, but a less serious problem for machines of those days, compared to using a few more bytes to store the length.