diff --git a/.gitignore b/.gitignore
index 59cabbb5..ffbfd6ac 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,7 @@
+build*
 .build*
+*.zip
+.lite-debug.log
+subprojects/lua
 subprojects/libagg
 sybprojects/lua
diff --git a/data/core/commands/core.lua b/data/core/commands/core.lua
index dbe08a41..870a2117 100644
--- a/data/core/commands/core.lua
+++ b/data/core/commands/core.lua
@@ -55,17 +55,30 @@ command.add(nil, {
   end,
 
   ["core:find-file"] = function()
+    local files = {}
+    for _, item in pairs(core.project_files) do
+      if item.type == "file" then
+        table.insert(files, item.filename)
+      end
+    end
     core.command_view:enter("Open File From Project", function(text, item)
       text = item and item.text or text
       core.root_view:open_doc(core.open_doc(text))
     end, function(text)
-      local files = {}
-      for _, item in pairs(core.project_files) do
-        if item.type == "file" then
-          table.insert(files, item.filename)
+      if text == "" then
+        local recent_files = {}
+        for i = 2, #core.visited_files do
+            table.insert(recent_files, core.visited_files[i])
         end
+        table.insert(recent_files, core.visited_files[1])
+        local other_files = common.fuzzy_match(files, "")
+        for i = 1, #other_files do
+          table.insert(recent_files, other_files[i])
+        end
+        return recent_files
+      else
+        return common.fuzzy_match(files, text)
       end
-      return common.fuzzy_match(files, text)
     end)
   end,
 
diff --git a/data/core/commands/doc.lua b/data/core/commands/doc.lua
index 0a4ee42c..a877225d 100644
--- a/data/core/commands/doc.lua
+++ b/data/core/commands/doc.lua
@@ -26,6 +26,10 @@ end
 
 local function insert_at_start_of_selected_lines(text, skip_empty)
   local line1, col1, line2, col2, swap = doc():get_selection(true)
+  if line2 > line1 and col2 == 1 then
+    line2 = line2 - 1
+    col2 = #doc().lines[line2]
+  end
   for line = line1, line2 do
     local line_text = doc().lines[line]
     if (not skip_empty or line_text:find("%S")) then
diff --git a/data/core/config.lua b/data/core/config.lua
index a9f106f6..4f58f825 100644
--- a/data/core/config.lua
+++ b/data/core/config.lua
@@ -16,5 +16,7 @@ config.line_height = 1.2
 config.indent_size = 2
 config.tab_type = "soft"
 config.line_limit = 80
+config.max_symbols = 2000
+config.max_project_files = 2000
 
 return config
diff --git a/data/core/init.lua b/data/core/init.lua
index fe74b344..5d023055 100644
--- a/data/core/init.lua
+++ b/data/core/init.lua
@@ -34,6 +34,8 @@ local function project_scan_thread()
     local all = system.list_dir(path) or {}
     local dirs, files = {}, {}
 
+    local entries_count = 0
+    local max_entries = config.max_project_files
     for _, file in ipairs(all) do
       if not common.match_pattern(file, config.ignore_files) then
         local file = (path ~= "." and path .. PATHSEP or "") .. file
@@ -41,6 +43,8 @@ local function project_scan_thread()
         if info and info.size < size_limit then
           info.filename = file
           table.insert(info.type == "dir" and dirs or files, info)
+          entries_count = entries_count + 1
+          if entries_count > max_entries then break end
         end
       end
     end
@@ -48,7 +52,10 @@ local function project_scan_thread()
     table.sort(dirs, compare_file)
     for _, f in ipairs(dirs) do
       table.insert(t, f)
-      get_files(f.filename, t)
+      if entries_count <= max_entries then
+        local subdir_t, subdir_count = get_files(f.filename, t)
+        entries_count = entries_count + subdir_count
+      end
     end
 
     table.sort(files, compare_file)
@@ -56,14 +63,19 @@ local function project_scan_thread()
       table.insert(t, f)
     end
 
-    return t
+    return t, entries_count
   end
 
   while true do
     -- get project files and replace previous table if the new table is
     -- different
-    local t = get_files(".")
+    local t, entries_count = get_files(".")
     if diff_files(core.project_files, t) then
+      if entries_count > config.max_project_files then
+        core.status_view:show_message("!", style.accent,
+          "Too many files in project directory: stopping reading at "..
+          config.max_project_files.." files according to config.max_project_files.")
+      end
       core.project_files = t
       core.redraw = true
     end
@@ -102,6 +114,7 @@ function core.init()
   core.threads = setmetatable({}, { __mode = "k" })
   core.project_files = {}
   core.redraw = true
+  core.visited_files = {}
 
   core.root_view = RootView()
   core.command_view = CommandView()
@@ -213,9 +226,23 @@ function core.reload_module(name)
 end
 
 
+function core.set_visited(filename)
+  for i = 1, #core.visited_files do
+    if core.visited_files[i] == filename then
+      table.remove(core.visited_files, i)
+      break
+    end
+  end
+  table.insert(core.visited_files, 1, filename)
+end
+
+
 function core.set_active_view(view)
   assert(view, "Tried to set active view to nil")
   if view ~= core.active_view then
+    if view.doc and view.doc.filename then
+      core.set_visited(view.doc.filename)
+    end
     core.last_active_view = core.active_view
     core.active_view = view
   end
@@ -450,12 +477,20 @@ end)
 
 
 function core.run()
+  local idle_iterations = 0
   while true do
     core.frame_start = system.get_time()
     local did_redraw = core.step()
     local need_more_work = run_threads()
     if not did_redraw and not need_more_work then
-      system.wait_event()
+      idle_iterations = idle_iterations + 1
+      -- do not wait of events at idle_iterations = 1 to give a chance at core.step to run
+      -- and set "redraw" flag.
+      if idle_iterations > 1 then
+        system.wait_event()
+      end
+    else
+      idle_iterations = 0
     end
     local elapsed = system.get_time() - core.frame_start
     system.sleep(math.max(0, 1 / config.fps - elapsed))
diff --git a/data/core/rootview.lua b/data/core/rootview.lua
index 389525f6..8bcc03da 100644
--- a/data/core/rootview.lua
+++ b/data/core/rootview.lua
@@ -396,14 +396,33 @@ function RootView:get_active_node()
   return self.root_node:get_node_for_view(core.active_view)
 end
 
+-- Get un unlocked node with at least one view.
+local function get_node_unlocked(node)
+  if not node.locked and #node.views > 0 then
+    return node
+  end
+  if node.type ~= "leaf" then
+    local a = get_node_unlocked(node.a)
+    if a then return a end
+    return get_node_unlocked(node.b)
+  end
+end
+
+function RootView:get_document_view()
+  local node = get_node_unlocked(self.root_node)
+  if node then
+    return node.views[1]
+  end
+end
 
 function RootView:open_doc(doc)
   local node = self:get_active_node()
-  if node.locked and core.last_active_view then
-    core.set_active_view(core.last_active_view)
+  if node.locked then
+    local default_view = self:get_document_view()
+    assert(default_view, "Cannot find an unlocked node to open the document.")
+    core.set_active_view(default_view)
     node = self:get_active_node()
   end
-  assert(not node.locked, "Cannot open doc on locked node")
   for i, view in ipairs(node.views) do
     if view.doc == doc then
       node:set_active_view(node.views[i])
diff --git a/data/plugins/autocomplete.lua b/data/plugins/autocomplete.lua
index 79e45133..7a43fd17 100644
--- a/data/plugins/autocomplete.lua
+++ b/data/plugins/autocomplete.lua
@@ -25,16 +25,28 @@ function autocomplete.add(t)
   autocomplete.map[t.name] =  { files = t.files or ".*", items = items }
 end
 
+local max_symbols = config.max_symbols or 2000
 
 core.add_thread(function()
   local cache = setmetatable({}, { __mode = "k" })
 
   local function get_symbols(doc)
+    if doc.disable_symbols then return {} end
     local i = 1
     local s = {}
+    local symbols_count = 0
     while i < #doc.lines do
       for sym in doc.lines[i]:gmatch(config.symbol_pattern) do
-        s[sym] = true
+        if not s[sym] then
+          symbols_count = symbols_count + 1
+          if symbols_count > max_symbols then
+            s = nil
+            doc.disable_symbols = true
+            collectgarbage('collect')
+            return {}
+          end
+          s[sym] = true
+        end
       end
       i = i + 1
       if i % 100 == 0 then coroutine.yield() end