The first release of TeX was in 1978. Dr. Knuth could have plausibly gotten results similar to yours by writing a 'classic' floating point algorithm: but IEEE

The first release of TeX was in 1978. Dr. Knuth could have plausibly gotten results similar to yours by writing a 'classic' floating point algorithm: but IEEE 734 [sic: 754] wasn't even published until 1985, so relying on hardware, let alone stable results from hardware, was completely impossible. This would also have been very, very, very. Very slow. Adding a constant factor of 20-50X to TeX wouldn't have been fun at all. TeX is also a famous program, the algorithms involved are well-known to anyone with an interest. The statement that it uses an expensive global strategy for layout is accurate.