Well your Extreme Pro 256gb already have higher speed then the Canon CF interface can handle. Even the 5D Mark IV can't handle above 105megabytes/s, and your card is 150mb/s both read and write. It won't get any faster the 5D3 interface is the limit, and those UDMA 7 CF cards has higher write speeds.
I have a Lexar 256gb 1066X card myself and don't get above 105mb/s writing to card in 5D3 camera. While doing a test with the card in cardreader i get 150mb/s both ways (read/write).
100mb/s isn't bad, i think most of those Red cameras with RedSSD's just write at 225mb/s and then we talk about 8k raw, ok shure they compress it when shooting 8k raw to fit into 225mb/s.
100mb/s is extreme for videorecording in raw with a camera that is over 6 years old, thats crazy over SIX years! And this high quality
