If zofrex is still reading, the text renderer replacement script has hit a pretty important milestone. It’s now roughly as fast as, or maybe even slightly faster than, the current script (it’s a low bar, but I still want to clear it). This was done through multithreading (rendering multiple subtitle images at the same time), which really speeds things up, but multithreading can also lead to subtle errors, so I’m still bugchecking that right now. I think there’s a good possibility this new script may be usable before the next release, so it’s now possible 12.0 may include it. I’m also finding and fixing bugs in the current renderer as I go, but I’m not backporting the fixes. The only quirk right now is that Chromium-based browsers have a tendency to occasionally leave zombie processes running, so when you use Chromium to render an image a quarter of a million times*, you could see some performance fallout.
* And yeah, it doesn’t really work in reverse, where you can use one Chromium instance to render thousands of images. There’s a hard image size limit, and I could maybe squeeze more than one image into a render operation, but the added complexity isn’t worth the payoff.