In VGA text mode the VGA hardware is doing the character->texture lookup for you, so you're just sending at most a glyph index worth of data to the card per cha

In VGA text mode the VGA hardware is doing the character->texture lookup for you, so you're just sending at most a glyph index worth of data to the card per character. With modern resolutions what they are, and 16-32 bpp color depths, combined with the unaccelerated dumb linear framebuffer you get with the console framebuffer drivers, it's quite slow relative to a classical VGA text mode. Even if you still had the same number of lines and columns of text as a classical VGA text mode, just the higher dpi and bpp will still be a lot of bytes for the CPU to move around without any DMA or GPU to assist. On top of that the VGA console driver in Linux used to exploit the hardware scrolling capabilities which basically just updated an offset register in the VGA instead of having to update the entire screen. IIRC you would lose your console scrollback history by switching virtual consoles because of this implementation. It was blazing fast but the VGA-resident contents were clobbered on VC switch.