We use Cairo for all rendering. Cairo has various backend implementations, and when it gets a Vulkan backend and you're using Ardour on a system with Vulkan available, it will be used.
We're not going to write renderers at a lower level than Cairo at any time in the foreseeable future.
Also, most of the issues with slow rendering are caused by your video interface driver and/or bugs in Cairo that we provide a few workarounds for already. Edit > Preferences > Appearance > Graphics Acceleration has two options ... you need to try all 4 possible combinations to exhaust the possibility that we've already solved the issue you are facing :)
Thanks for the tips, I will try that and try to get some perf, I am currently compiling Ardour 6.9 :)
On a side note, I don't mean to be the bearer of bad news but I think you need a better plan than this, cairo has been in various states of inactivity and deep maintenance mode over the last several years, if anything more backends will be removed, not added. Also, cairo is an immediate mode-style renderer following the PDF imaging model made for print -- it's fundamentally the wrong approach for high performance rendering. You may not see much improvement even if it did have a Vulkan backend.
We're not going to write renderers at a lower level than Cairo at any time in the foreseeable future.
Also, most of the issues with slow rendering are caused by your video interface driver and/or bugs in Cairo that we provide a few workarounds for already. Edit > Preferences > Appearance > Graphics Acceleration has two options ... you need to try all 4 possible combinations to exhaust the possibility that we've already solved the issue you are facing :)