Way back in the 90s when I got my first "modern" PC, it was a 486 DX-2, a 50 MHz processor, with 4 MB of RAM.
That 4 MB of RAM just barely allowed it to run DOOM. I had to unload some unnecessary device drivers, which meant rebooting the computer to apply a different config.sys and autoexec.bat, but it would run it.
At one point, I was thinking about some memory structures I could implement to calculate shading faster, but it seemed they would require a lot of memory. So I did some math and found they would require 4 MB of RAM for this one relatively small aspect of the game. I thought to myself "Why, that's nothing at all!"
Interesting how times have changed. Back then we couldn't waste 4 MB if we wanted to. Now it's hardly worth the time it takes to think about it. Many single textures in the game consume 4 MB of video RAM. That some part of the code requires 4 MB to speed up some calculations is relatively inconsequential.