perf(picker): cache wether ts lang exists and disable smooth scrolling on big files

lua/snacks/picker/core/input.lua

@@ -78,7 +78,7 @@ function M.new(picker)
       vim.schedule(function()
         input.picker:find({ refresh = false })
       end)
-    end, { ms = picker.opts.live and 100 or 30 }),
+    end, { ms = picker.opts.live and 200 or 30 }),
     { buf = true }
   )
   return self

lua/snacks/picker/core/picker.lua

@@ -499,7 +499,7 @@ M._throttled_preview = M._show_preview
 -- otherwise throttle the preview.
 function M:show_preview()
   if not self.preview.item then
-    self:_show_preview()
+    return self:_show_preview()
   end
   return self:_throttled_preview()
 end

lua/snacks/picker/core/preview.lua

@@ -10,6 +10,7 @@
 ---@field winhl string
 ---@field title? string
 ---@field split_layout? boolean
+---@field opts? snacks.picker.previewers.Config
 local M = {}
 M.__index = M
 
@@ -28,6 +29,7 @@ local ns_loc = vim.api.nvim_create_namespace("snacks.picker.preview.loc")
 ---@param main? number
 function M.new(opts, main)
   local self = setmetatable({}, M)
+  self.opts = opts.previewers
   self.winhl = Snacks.picker.highlight.winhl("SnacksPickerPreview", { CursorLine = "Visual" })
   local win_opts = Snacks.win.resolve(
     {
@@ -237,11 +239,10 @@ function M:highlight(opts)
       filename = opts.file,
     })
   end
-  local lang = opts.lang or ft and vim.treesitter.language.get_lang(ft)
-  if not (lang and pcall(vim.treesitter.start, self.win.buf, lang)) then
-    if ft then
-      vim.bo[self.win.buf].syntax = ft
-    end
+  self:check_big()
+  local lang = Snacks.picker.highlight.get_lang({ lang = opts.lang, ft = ft })
+  if not (lang and pcall(vim.treesitter.start, self.win.buf, lang)) and ft then
+    vim.bo[self.win.buf].syntax = ft
   end
 end
 
@@ -312,6 +313,23 @@ function M:loc()
   end
 end
 
+function M:check_big()
+  local big = self:is_big()
+  vim.b[self.win.buf].snacks_scroll = not big
+end
+
+function M:is_big()
+  local lines = vim.api.nvim_buf_line_count(self.win.buf)
+  if lines > 1000 then
+    return true
+  end
+  local path = self.item and self.item.file and Snacks.picker.util.path(self.item)
+  if path and vim.fn.getfsize(path) > 1.5 * 1024 * 1024 then
+    return true
+  end
+  return false
+end
+
 ---@param lines string[]
 function M:set_lines(lines)
   vim.bo[self.win.buf].modifiable = true

lua/snacks/picker/util/highlight.lua

@@ -1,6 +1,21 @@
 ---@class snacks.picker.highlight
 local M = {}
 
+M.langs = {} ---@type table<string, boolean>
+
+---@param opts? {lang?:string, ft?:string}
+function M.get_lang(opts)
+  opts = opts or {}
+  local lang = opts.lang or (opts.ft and vim.treesitter.language.get_lang(opts.ft)) or nil
+  if not lang then
+    return
+  end
+  if M.langs[lang] == nil then
+    M.langs[lang] = pcall(vim.treesitter.language.add, lang)
+  end
+  return M.langs[lang] and lang or nil
+end
+
 ---@param opts? {buf?:number, code?:string, ft?:string, lang?:string, file?:string, extmarks?:boolean}
 function M.get_highlights(opts)
   opts = opts or {}
@@ -13,7 +28,7 @@ function M.get_highlights(opts)
     or (opts.buf and vim.bo[opts.buf].filetype)
     or (opts.file and vim.filetype.match({ filename = opts.file, buf = 0 }))
     or vim.bo.filetype
-  local lang = opts.lang or vim.treesitter.language.get_lang(ft)
+  local lang = M.get_lang({ lang = opts.lang, ft = ft })
   local parser ---@type vim.treesitter.LanguageTree?
   if lang then
     local ok = false