[avianlyric]

Is there a good reason that people don’t use curved traces anymore, except that it easier for CAD software?

When traces where done by hand, they used to be curved and flowing, and frequently looked very elegant. And occasionally you see a super high speed design that’s a bit curvy today.

[Gibbon1]

I think the answer is the discontinuity you get from a sharp bend is smaller than the highest frequency/wavelength in the signal. So you don't get any reflections off it. The way I think is the length of the wave front heading down the trace is much longer than the size of the bend. I think very high speed stuff can start having trouble with via's.

I think curved traces were used make layout easier when running tape. Bending the tape is easier than doing a cut to shift the trace over.

And safer, a problem with old tape layouts is it's easy enough to knock off a small section of tape. Old draftsman I worked with would check the layout against a blue print on a light table to make sure nothing was amiss before making mods. He also got really antsy if anyone was rummaging around in the drawers holding PCB layouts.

[davrosthedalek]

High speed designs definitely do not like corners, especially fast serial interconnects are often problematic (they tend to have really high clocks), think PCIe, USB3,...

[madengr]

Sharp curves radiate more than mitered corners. The curves has two unequal current paths; inner and outer radius. Any imbalance results in an inductance. I assume it takes longer to photoplot too as the machine has to interpolate around the curves.