Refresh line_types cause performance degradation(probably)

[Xie Zejian]

During may hack in #88, I found that jupynium will call cells.line_types_entire_buf even without editing. That seems result in slow scroll in large files when jupynium is enabled.

[Kiyoon Kim]

Does this happen with the PR or even without the PR? Maybe the function return table can be cached and reused if the buffer is not changed

[Kiyoon Kim]

Is it because of the get_fold implementation in #88? Maybe ufo callback is being called too often?

[Xie Zejian]

The problem persisted after I set dev=false so that's should be irrelevant with my PR.
Could you confirm this by something like

-- jupynium.nvim/lua/jupynium/highlighter.lua
function M.update()
  if not M.is_enabled() then
    return
  end

  local end_of_file = vim.fn.line "$"
  local line_types = cells.line_types_entire_buf()
  print("Call me")

Maybe the function return table can be cached and reused if the buffer is not changed

Yeah I agree this is a clever approach