Why is rendering AVI to MP4 so slow???

[MisterAdvent]

I've upgraded the machine with SSDs that are capable of 10GB/sec. But I'm rendering SD DV SDI to SD DV MP4 at around 12KB/s - when it writes.  It's "chunking,"  little write bursts that corresspond to 3D activity on the nVidia GPU and CPU.  Nothing happens on the Intel GPU. 

Latest nVidia driver on a 2080ti.

This used to render quickly.  What has changed?

AME 25.2 build 74 Beta

[MisterAdvent]

I just ran an experiment and exported the DV AVI to a 720p MP4 (16:9 with pillarbox).  It went full tilt. What took 20 minutes in 4:3 was done in 2 minutes flat. 

So what happend to 4:3 support???

[MisterAdvent]

So now I'm checking other settings.  It is speedy with the Vimeo 480p settings, either widescreen or 4:3. 

If I switch interlacing on, it does the slowdown.

Except with the "Match Source - Adaptive High Resolution" setting. With interlacing set to Progressive, it slows down (but not as much as with it on).