So you want speed huh ?
Talking edge restoring not honing I gather ?

Diamond plates will do the speed aspect but you will lose time trying to fix the deep scratches later. Catch 22.
One of the fastest synthetics I've used is the Shapton Pro/Ha No Kuromaku line especially on slurry. Like diamond plates they can be pretty scratchy on razors in the coarse grits. 320-1000 grit

It may be better to compromise that extreme cutting speed for a more razor friendly stone.
i'm very impressed with the Chocera line in that regard but can only speak re the 1k & 5k as yet. The 1k doesn't have the Pro's speed but the razor doesn't need so much "healing" afterwards.
I'd like to try the coarser Chocera grits. If they work as I expect I could easily see myself retiring my Shaptons to knife work.