Direct access to the text mode segment (0xb800 if I remember correctly) was much faster. The fonts were blitted out by hardware for every scan line, so you just changed the few thousand bytes of video memory at hundreds of thousands of bytes per second.
The actual usable bandwidth was always much lower, somewhere between 80kB/s to a bit over 380kB/s, depending on how you were using the bus, because the cpu needed to fetch its instructions on the same bus. In a way, the bus was usually always running at 1.19MB/s though, because all the basic devices (ROM, RAM, common simple ISA cards) were able to always respond in the basic 4-cycle transfer, it's just that most cycles were spent fetching instructions instead of actual data.
Later machines made the bus faster by increasing width, increasing clocks, and dropping one mandatory wait state at AT for 5.55MB/s theoretical, and dropping the last wait state in the fast clones for 8.33MB/s theoretical.