I am trying to use Emacs for developing in Lua, and installed a Lua mode for that. After doing this I was unhappy about the background and changed it by applying the face of my text mode (which I configred by myself). It worked, but now the modified settings for Lua mode are being applied with the significant delay (3-5 sec) after opening a Lua file.

Both .emacs and lua-mode.el are byte-compiled.

Any advice?