Canon RF 100-300 f/2.8 IS USM

[Kayaker72]

I think it slows down a little with the 2x, but the AF is so fast natively that any difference is barely perceptible.

Thanks. This seems like a big improvement over previous lenses, especially EF, with a 2x TC. It'll be interesting to see about AF speed and IQ if Canon does release some sort of 0, 1.4, 2x TC.