I thought it was pretty crazy that a tweak to prevent XFree86 from breaking on 64bit systems + support for the ELF small code execution model would later result

I thought it was pretty crazy that a tweak to prevent XFree86 from breaking on 64bit systems + support for the ELF small code execution model would later result in pthread_create overhead so large that creating threads on a P4 would be as slow as creating threads on a 386. But, hey, maybe it isn't that crazy to you.