loader/boot fonts are painfully small (again)

[Yuri Pankov]

Lenovo P51 laptop, 15'' 4k (3840x2160) display.

Booting from the latest available current snapshot (20210107), fonts
were at least readable; updating to the latest bits (manually installing
new loader as well) made them really small -- terminal size reported by
stty is 480x135.

I have also noticed large delays between different loader screens,
probably caused by very slow screen blanking given the terminal size?