Compute indentexpr for the whole buffer and cache it

[xzbdmw]

Is your feature request related to a problem? Please describe.
In a lua file, ts's indent method takes 0.02s which is a noticeable delay when I type o. After trying zed, which also use treessitter to indent, I found their speed is super fast(new line).
With some curiosity to scan their code, I found zed computes an indent map that is (line->indent) for the whole buffer and that's where the speed comes from. I think nvim-treessitter can adapt that pattern too.

relevant code

[xzbdmw]

For simplicity I want to cache get_indent() call's result at CursorMove and apply result when I type o so eliminating latency, but it turns out that when I type o, neovim adds a new line below and change cursor position at first(not showed in ui) and then calls indentexpr, for that reason, calling get_indent() mannally don't works, do you have any suggestions to get real indent?