If anyone wants to do this in DOS, one thing I learned from the 1991 BLUE Book is that BLOAD can be used to load a binary file straight to graphics card memory. https://github.com/robhagemans/hoard-of-gwbasic

There was a site hosting the author's freeware utilities (now only on the web archive?), and one is a graphics editor made for that purpose ("EBS: Screen editor for BLOAD pages"):

https://web.archive.org/web/20060410121551/http://scottserve...

From a quick search BLOAD is available in Commodore BASIC as well. Would be interesting to hear how it compares to the optimized loop that PRINTs the image, if the same trick works on a C64?

* No... BLOAD was added in some later version, e.g. for C128, not any of the versions running on C64 https://www.c64-wiki.com/wiki/BASIC_7.0#Commodore_BASIC_Comm... ... But I guess the speed of reading a few kB from a C64 disk drive compared to a 1991 PC hard disk may make it a pretty bad idea anyway if speed is important. On the other hand it would make the program itself smaller and faster to load, so difficult to guess if the total time to render the screen would have increased or not.

I mean, it's basic knowledge that in BASIC printing a whole line is faster than poking characters in a loop. You can also simulate curses positioning by using strings of control characters https://www.c64-wiki.com/wiki/control_character No need to have a real C64 to evaluate most things, there are quite accurate emulators, too.