Given an advanced civilization which has the technology to exceed light speed, what plausible explanation could there be for said civilization for being unable to fabricate microchips with transistor sizes smaller than a couple micrometers? (Effectively no smaller than what was being used in the 1980s.)
Notes about the world
The galaxy is essentially dotted with small empires which less resemble empires and more resemble corporations. Each empire essentially is it's own brand and they all attempt to sell a myriad of products throughout the galaxy. The galactic market is highly competitive, especially given the widespread dissemination of technology which can enables almost any large enough group of people to build a small empire ruling over a couple planets within a couple years. In a universe where massive computational grids are required for space travel, a universe where large empires spend double digit percentages of their total budget on microchips, there would be an immense competition to develop CPUs with ever greater performance. Anybody that succeeded in shrinking the transistor size down to, say, less than 1 uM would be able to amass capital incredibly quick and would probably grow into one of the largest empires in the galaxy. And yet, somehow, transistor sizes never really got much below 5 uM. Why?