diff --git a/README.md b/README.md
index 9ceaf2a..a3ca314 100644
--- a/README.md
+++ b/README.md
@@ -198,8 +198,11 @@ require("quicker").setup({
   -- Keep the cursor to the right of the filename and lnum columns
   constrain_cursor = true,
   highlight = {
-    -- Use treesitter highlighting
+    -- Attach treesitter parser to qf buffer, highlight text in real time as you edit.
     treesitter = true,
+    -- Do not register callbacks when buffer line counts exceed this limit. In other words,
+    -- highlight won't get updated as you edit.
+    max_lines = 10000,
     -- Use LSP semantic token highlighting
     lsp = true,
     -- Load the referenced buffers to apply more accurate highlights (may be slow)
diff --git a/lua/quicker/config.lua b/lua/quicker/config.lua
index f60b978..424b50f 100644
--- a/lua/quicker/config.lua
+++ b/lua/quicker/config.lua
@@ -3,6 +3,7 @@ local default_config = {
   opts = {
     buflisted = false,
     number = false,
+    concealcursor = "nvic",
     relativenumber = false,
     signcolumn = "auto",
     winfixheight = true,
@@ -26,8 +27,11 @@ local default_config = {
   -- Keep the cursor to the right of the filename and lnum columns
   constrain_cursor = true,
   highlight = {
-    -- Use treesitter highlighting
+    -- Attach treesitter parser to qf buffer, highlight text in real time as you edit.
     treesitter = true,
+    -- Do not register callbacks when buffer line counts exceed this limit. In other words,
+    -- highlight won't get updated as you edit.
+    max_lines = 10000,
     -- Use LSP semantic token highlighting
     lsp = true,
     -- Load the referenced buffers to apply more accurate highlights (may be slow)
@@ -155,6 +159,7 @@ end
 
 ---@class (exact) quicker.HighlightConfig
 ---@field treesitter boolean
+---@field max_lines integer
 ---@field lsp boolean
 ---@field load_buffers boolean
 
diff --git a/lua/quicker/display.lua b/lua/quicker/display.lua
index 5c551d3..f603d02 100644
--- a/lua/quicker/display.lua
+++ b/lua/quicker/display.lua
@@ -5,7 +5,9 @@ local util = require("quicker.util")
 
 local M = {}
 
-local EM_QUAD = " "
+-- A EM_QUAD and a space, we include an extra space before the real text, because it
+-- avoids strange cases such as no highlight when insert at start of qf text.
+local EM_QUAD = "  "
 local EM_QUAD_LEN = EM_QUAD:len()
 M.EM_QUAD = EM_QUAD
 M.EM_QUAD_LEN = EM_QUAD_LEN
@@ -216,27 +218,6 @@ local function add_item_highlights_from_buf(qfbufnr, item, line, lnum)
       offset = offset - item_space
     end
 
-    -- Add treesitter highlights
-    if config.highlight.treesitter then
-      for _, hl in ipairs(highlight.buf_get_ts_highlights(item.bufnr, item.lnum)) do
-        local start_col, end_col, hl_group = hl[1], hl[2], hl[3]
-        if end_col == -1 then
-          end_col = src_line:len()
-        end
-        -- If the highlight starts at the beginning of the source line, then it might be off the
-        -- buffer in the quickfix because we've removed leading whitespace. If so, clamp the value
-        -- to 0. Except, for some reason 0 gives incorrect results, but -1 works properly even
-        -- though -1 should indicate the *end* of the line. Not sure why this work, but it does.
-        local hl_start = math.max(-1, start_col + offset)
-        vim.api.nvim_buf_set_extmark(qfbufnr, ns, lnum - 1, hl_start, {
-          hl_group = hl_group,
-          end_col = end_col + offset,
-          priority = 100,
-          strict = false,
-        })
-      end
-    end
-
     -- Add LSP semantic token highlights
     if config.highlight.lsp then
       for _, hl in ipairs(highlight.buf_get_lsp_highlights(item.bufnr, item.lnum)) do
@@ -267,6 +248,10 @@ local function highlight_buffer_when_entered(qfbufnr, info)
       vim.b[qfbufnr].pending_highlight = nil
       info.start_idx = 1
       info.end_idx = vim.api.nvim_buf_line_count(qfbufnr)
+      info.regions = {}
+      info.region_count = 0
+      info.empty_regions = {}
+      info.ft = {}
       schedule_highlights(info)
     end,
   })
@@ -339,23 +324,44 @@ add_qf_highlights = function(info)
         loaded = true
       end
 
-      if loaded then
-        add_item_highlights_from_buf(qfbufnr, item, line, i)
-      elseif config.highlight.treesitter then
+      local ft = info.ft[item.bufnr]
+      if ft == nil then
+        ft = loaded and vim.bo[item.bufnr].filetype or vim.filetype.match({ buf = item.bufnr })
+        info.ft[item.bufnr] = ft
+      end
+
+      if config.highlight.treesitter and ft then
+        info.regions[ft] = info.regions[ft] or {}
+        info.region_count = info.region_count + 1
+        info.empty_regions[ft] = info.empty_regions[ft] or {}
         local filename = vim.split(line, EM_QUAD, { plain = true })[1]
-        local offset = filename:len() + EM_QUAD_LEN
-        local text = line:sub(offset + 1)
-        for _, hl in ipairs(highlight.get_heuristic_ts_highlights(item, text)) do
-          local start_col, end_col, hl_group = hl[1], hl[2], hl[3]
-          start_col = start_col + offset
-          end_col = end_col + offset
-          vim.api.nvim_buf_set_extmark(qfbufnr, ns, i - 1, start_col, {
-            hl_group = hl_group,
-            end_col = end_col,
-            priority = 100,
-            strict = false,
+
+        -- Note: we must include the new line character, when multiple lines are treated as one
+        -- range, without "\n" causes all the problems, for example:
+        --
+        -- tests/tmp/expand_1.lua ┃ 2┃-- a comment
+        -- tests/tmp/expand_1.lua ┃ 3┃local a = 1
+        --
+        -- The parser will treat this as "-- a commentlocal a = 1".
+        local region = {
+          i - 1,
+          filename:len() + EM_QUAD_LEN - 1, -- skip EM_QUAD but include a space
+          i,
+          0,
+        }
+        info.previous_item = info.previous_item or item
+        if info.previous_item.bufnr == item.bufnr and info.previous_item.lnum == item.lnum - 1 then
+          -- Merge current range with previous one, parse them together.
+          table.insert(info.regions[ft][#info.regions[ft]], region)
+        else
+          table.insert(info.regions[ft], {
+            region,
           })
         end
+        info.previous_item = item
+      end
+      if loaded then
+        add_item_highlights_from_buf(qfbufnr, item, line, i)
       end
     end
 
@@ -383,6 +389,12 @@ add_qf_highlights = function(info)
       return
     end
   end
+  if config.highlight.treesitter then
+    local register_cbs = info.region_count <= config.highlight.max_lines
+    -- cleanup previous regions each time we call setqflist.
+    require("quicker.treesitter").attach(qf_list.qfbufnr, info.empty_regions, register_cbs)
+    require("quicker.treesitter").attach(qf_list.qfbufnr, info.regions, register_cbs)
+  end
 
   vim.api.nvim_buf_clear_namespace(qf_list.qfbufnr, ns, info.end_idx, -1)
 end
@@ -425,6 +437,11 @@ end
 ---@field id integer
 ---@field start_idx integer
 ---@field end_idx integer
+---@field regions table<string, Range4[][]>
+---@field region_count integer
+---@field empty_regions table<string, Range4[][]>
+---@field ft table<integer, string|nil>
+---@field previous_item QuickFixItem
 ---@field winid integer
 ---@field quickfix 1|0
 ---@field force_bufload? boolean field injected by us to control if we're forcing a bufload for the syntax highlighting
@@ -561,6 +578,10 @@ function M.quickfixtextfunc(info)
             virt_text_pos = "inline",
             invalidate = true,
           })
+        vim.api.nvim_buf_set_extmark(qf_list.qfbufnr, ns, lnum - 1, end_col, {
+          end_col = end_col + EM_QUAD_LEN - 1,
+          conceal = "",
+        })
         idmap[id] = lnum
 
         -- Highlight the filename
@@ -581,6 +602,10 @@ function M.quickfixtextfunc(info)
           virt_lines = { header },
           virt_lines_above = true,
         })
+        -- vim.api.nvim_buf_set_extmark(qf_list.qfbufnr, ns, lnum - 1, end_col, {
+        --   end_col = end_col + EM_QUAD_LEN - 1,
+        --   conceal = "",
+        -- })
       end
     end
   end
@@ -588,6 +613,10 @@ function M.quickfixtextfunc(info)
 
   -- If we just rendered the last item, add highlights
   if info.end_idx == #items then
+    info.regions = {}
+    info.region_count = 0
+    info.empty_regions = {}
+    info.ft = {}
     schedule_highlights(info)
 
     if qf_list.qfbufnr > 0 then
diff --git a/lua/quicker/highlight.lua b/lua/quicker/highlight.lua
index a7323aa..0b52c2b 100644
--- a/lua/quicker/highlight.lua
+++ b/lua/quicker/highlight.lua
@@ -19,71 +19,6 @@ local function get_highlight_query(lang)
   end
 end
 
----@param bufnr integer
----@param lnum integer
----@return quicker.TSHighlight[]
-function M.buf_get_ts_highlights(bufnr, lnum)
-  local filetype = vim.bo[bufnr].filetype
-  if not filetype or filetype == "" then
-    filetype = vim.filetype.match({ buf = bufnr }) or ""
-  end
-  local lang = vim.treesitter.language.get_lang(filetype) or filetype
-  if lang == "" then
-    return {}
-  end
-  local ok, parser = pcall(vim.treesitter.get_parser, bufnr, lang)
-  if not ok or not parser then
-    return {}
-  end
-
-  local row = lnum - 1
-  if not parser:is_valid() then
-    parser:parse(true)
-  end
-
-  local highlights = {}
-  parser:for_each_tree(function(tstree, tree)
-    if not tstree then
-      return
-    end
-
-    local root_node = tstree:root()
-    local root_start_row, _, root_end_row, _ = root_node:range()
-
-    -- Only worry about trees within the line range
-    if root_start_row > row or root_end_row < row then
-      return
-    end
-
-    local query = get_highlight_query(tree:lang())
-
-    -- Some injected languages may not have highlight queries.
-    if not query then
-      return
-    end
-
-    for capture, node, metadata in query:iter_captures(root_node, bufnr, row, root_end_row + 1) do
-      if capture == nil then
-        break
-      end
-
-      local range = vim.treesitter.get_range(node, bufnr, metadata[capture])
-      local start_row, start_col, _, end_row, end_col, _ = unpack(range)
-      if start_row > row then
-        break
-      end
-      local capture_name = query.captures[capture]
-      local hl = string.format("@%s.%s", capture_name, tree:lang())
-      if end_row > start_row then
-        end_col = -1
-      end
-      table.insert(highlights, { start_col, end_col, hl })
-    end
-  end)
-
-  return highlights
-end
-
 ---@class quicker.LSPHighlight
 ---@field [1] integer start_col
 ---@field [2] integer end_col
@@ -157,50 +92,6 @@ function M.buf_get_lsp_highlights(bufnr, lnum)
   return lsp_highlights
 end
 
----@param item QuickFixItem
----@param line string
----@return quicker.TSHighlight[]
-M.get_heuristic_ts_highlights = function(item, line)
-  local filetype = vim.filetype.match({ buf = item.bufnr })
-  if not filetype then
-    return {}
-  end
-
-  local lang = vim.treesitter.language.get_lang(filetype)
-  if not lang then
-    return {}
-  end
-
-  local has_parser, parser = pcall(vim.treesitter.get_string_parser, line, lang)
-  if not has_parser then
-    return {}
-  end
-
-  local root = parser:parse(true)[1]:root()
-  local query = vim.treesitter.query.get(lang, "highlights")
-  if not query then
-    return {}
-  end
-
-  local highlights = {}
-  for capture, node, metadata in query:iter_captures(root, line) do
-    if capture == nil then
-      break
-    end
-
-    local range = vim.treesitter.get_range(node, line, metadata[capture])
-    local start_row, start_col, _, end_row, end_col, _ = unpack(range)
-    local capture_name = query.captures[capture]
-    local hl = string.format("@%s.%s", capture_name, lang)
-    if end_row > start_row then
-      end_col = -1
-    end
-    table.insert(highlights, { start_col, end_col, hl })
-  end
-
-  return highlights
-end
-
 function M.set_highlight_groups()
   if vim.tbl_isempty(vim.api.nvim_get_hl(0, { name = "QuickFixHeaderHard" })) then
     vim.api.nvim_set_hl(0, "QuickFixHeaderHard", { link = "Delimiter", default = true })
diff --git a/lua/quicker/treesitter.lua b/lua/quicker/treesitter.lua
new file mode 100644
index 0000000..c041eb8
--- /dev/null
+++ b/lua/quicker/treesitter.lua
@@ -0,0 +1,103 @@
+local config = require("quicker.config")
+
+local M = {}
+
+local cache = {} ---@type table<number, table<string,{parser: vim.treesitter.LanguageTree, highlighter:vim.treesitter.highlighter, enabled:boolean}>>
+local ns = vim.api.nvim_create_namespace("quicker.treesitter")
+
+local TSHighlighter = vim.treesitter.highlighter
+
+local function wrap(name)
+  return function(_, win, buf, ...)
+    if not cache[buf] then
+      return false
+    end
+    for _, hl in pairs(cache[buf] or {}) do
+      if hl.enabled then
+        TSHighlighter.active[buf] = hl.highlighter
+        TSHighlighter[name](_, win, buf, ...)
+      end
+    end
+    TSHighlighter.active[buf] = nil
+  end
+end
+
+M.did_setup = false
+function M.setup()
+  if M.did_setup then
+    return
+  end
+  M.did_setup = true
+
+  vim.api.nvim_set_decoration_provider(ns, {
+    on_win = wrap("_on_win"),
+    on_line = wrap("_on_line"),
+  })
+
+  vim.api.nvim_create_autocmd("BufWipeout", {
+    group = vim.api.nvim_create_augroup("quicker.treesitter.hl", { clear = true }),
+    callback = function(ev)
+      cache[ev.buf] = nil
+    end,
+  })
+end
+
+---@alias quicker.LangRegions table<string, Range4[][]>
+
+---@param buf number
+---@param regions quicker.LangRegions
+---@param register_cbs boolean
+function M.attach(buf, regions, register_cbs)
+  M.setup()
+  cache[buf] = cache[buf] or {}
+  for lang in pairs(cache[buf]) do
+    cache[buf][lang].enabled = regions[lang] ~= nil
+  end
+
+  for lang in pairs(regions) do
+    M._attach_lang(buf, lang, regions[lang], register_cbs)
+  end
+end
+
+---@param buf number
+---@param lang string
+---@param regions quicker.LangRegions
+---@param register_cbs boolean
+function M._attach_lang(buf, lang, regions, register_cbs)
+  cache[buf] = cache[buf] or {}
+
+  if not cache[buf][lang] then
+    local ok, parser
+    if register_cbs then
+      ok, parser = pcall(vim.treesitter.get_parser, buf, lang)
+    else
+      ok, parser = pcall(vim.treesitter.languagetree.new, buf, lang)
+    end
+    if not ok then
+      return
+    end
+    parser:set_included_regions(vim.deepcopy(regions))
+    cache[buf][lang] = {
+      parser = parser,
+      highlighter = TSHighlighter.new(parser),
+    }
+  end
+  cache[buf][lang].enabled = true
+  local parser = cache[buf][lang].parser
+
+  parser:set_included_regions(vim.deepcopy(regions))
+  -- Run a full parse for all included regions. There are two reasons:
+  -- 1. When we call `vim.treesitter.get_parser`, we have not set any
+  --    injection ranges.
+  -- 2. If this is not called, the highlighter will do incremental parsing,
+  --    which means it only parses visible areas (the on_win and on_line callback),
+  --    so if we modify the buffer, unvisited area's state get unsynced.
+  pcall(parser.parse, parser, true)
+  -- Hack: we need to manually perform an edit, otherwise delete an entire line
+  -- will cause all highlights to disappear.
+  vim.api.nvim_buf_call(buf, function()
+    vim.cmd([[norm! "_xu]])
+  end)
+end
+
+return M