godot-docs/development/compiling/optimizing_for_size.rst

.. _doc_optimizing_for_size:

Optimizing a build for size
===========================

.. highlight:: shell

Rationale
---------

Sometimes, it is desired to optimize a build for size rather than speed.
This means not compiling unused functions from the engine, as well as using
specific compiler flags to aid on decreasing build size.
Common situations include creating builds for mobile and Web platforms.

This tutorial aims to give an overview on different methods to create
a smaller binary. Before continuing, it is recommended to read the previous tutorials
on compiling Godot for each platform.

The options below are listed from the most important (greatest size savings)
to the least important (lowest size savings).

Stripping binaries
------------------

- **Space savings:** Very high
- **Difficulty:** Easy
- **Performed in official builds:** Yes

If you build Windows (MinGW), Linux or macOS binaries from source, remember to
strip debug symbols from binaries by installing the ``strip`` package from your
distribution then running:

::

    strip path/to/godot.binary

On Windows, ``strip.exe`` is included in most MinGW toolchain setups.

This will reduce the size of compiled binaries by a factor between 5× and 10×.
The downside is that crash backtraces will no longer provide accurate information
(which is useful for troubleshooting the cause of a crash).
:ref:`C++ profilers <doc_using_cpp_profilers>` will also no longer be able to display
function names (this does not affect the built-in GDScript profiler).

.. note::

    The above command will not work on Windows binaries compiled with MSVC
    and platforms such as Android and HTML5. Instead, pass ``debug_symbols=no``
    on the SCons command line when compiling.

Optimizing for size instead of speed
------------------------------------

- **Space savings:** High
- **Difficulty:** Easy
- **Performed in official builds:** Yes, but only for HTML5

Godot 3.1 onwards allows compiling using size optimizations (instead of speed).
To enable this, set the ``optimize`` flag to ``size``:

::

    scons p=windows target=release tools=no optimize=size

Some platforms such as WebAssembly already use this mode by default.

Compiling with link-time optimization
-------------------------------------

- **Space savings:** High
- **Difficulty:** Easy
- **Performed in official builds:** Yes

Enabling link-time optimization produces more efficient binaries, both in
terms of performance and file size. It works by eliminating duplicate
template functions and unused code. It can currently be used with the GCC
and MSVC compilers:

::

    scons p=windows target=release tools=no use_lto=yes

Linking becomes much slower and more RAM-consuming with this option,
so it should be used only for release builds:

- When compiling the ``master`` branch, you need to have at least 8 GB of RAM
  available for successful linking with LTO enabled.
- When compiling the ``3.x`` branch, you need to have at least 6 GB of RAM
  available for successful linking with LTO enabled.

Disabling 3D
------------

- **Space savings:** Moderate
- **Difficulty:** Easy
- **Performed in official builds:** No

For 2D games, having the whole 3D engine available usually makes no sense. Because of this, there is a build flag to disable it:

::

    scons p=windows target=release tools=no disable_3d=yes

Tools must be disabled in order to use this flag, as the editor is not designed
to operate without 3D support. Without it, the binary size can be reduced
by about 15%.

Disabling advanced GUI objects
------------------------------

- **Space savings:** Moderate
- **Difficulty:** Easy
- **Performed in official builds:** No

Most small games don't require complex GUI controls such as Tree, ItemList,
TextEdit or GraphEdit. They can be disabled using a build flag:

::

    scons p=windows target=release tools=no disable_advanced_gui=yes

This is everything that will be disabled:

- FileDialog
- PopupMenu
- Tree
- TextEdit
- TreeItem
- OptionButton
- SpinBox
- ColorPicker
- ColorPickerButton
- RichTextLabel
- RichTextEffect
- CharFXTransform
- PopupDialog
- WindowDialog
- AcceptDialog
- ConfirmationDialog
- MarginContainer
- ViewportContainer
- SplitContainer
- HSplitContainer
- GraphNode
- GraphEdit

Disabling unwanted modules
--------------------------

- **Space savings:** Very low to moderate depending on modules
- **Difficulty:** Medium to hard depending on modules
- **Performed in official builds:** No

A lot of Godot's functions are offered as modules.
You can see a list of modules with the following command:

::

    scons --help

The list of modules that can be disabled will appear, together with all
build options. If you are working on a simple 2D game, you could disable
a lot of them:

::

    scons p=windows target=release tools=no module_arkit_enabled=no module_assimp_enabled=no module_bmp_enabled=no module_bullet_enabled=no module_camera_enabled=no module_csg_enabled=no module_dds_enabled=no module_enet_enabled=no module_etc_enabled=no module_gdnative_enabled=no module_gridmap_enabled=no module_hdr_enabled=no module_jsonrpc_enabled=no module_mbedtls_enabled=no module_mobile_vr_enabled=no module_opensimplex_enabled=no module_opus_enabled=no module_pvr_enabled=no module_recast_enabled=no module_regex_enabled=no module_squish_enabled=no module_svg_enabled=no module_tga_enabled=no module_theora_enabled=no module_tinyexr_enabled=no module_upnp_enabled=no module_vhacd_enabled=no module_vorbis_enabled=no module_webm_enabled=no module_webrtc_enabled=no module_websocket_enabled=no module_xatlas_unwrap_enabled=no

If this proves not to work for your use case, you should review the list of
modules and see which ones you actually still need for your game (e.g. you
might want to keep networking-related modules, regex support, or theora/webm
to play videos).

Alternatively, you can supply a list of disabled modules by creating
``custom.py`` at the root of the source, with the contents similar to the
following:

.. code-block:: python

    # custom.py

    module_arkit_enabled = "no"
    module_assimp_enabled = "no"
    module_bmp_enabled = "no"
    module_bullet_enabled = "no"
    module_camera_enabled = "no"
    module_csg_enabled = "no"
    module_dds_enabled = "no"
    module_enet_enabled = "no"
    module_etc_enabled = "no"
    module_gdnative_enabled = "no"
    module_gridmap_enabled = "no"
    module_hdr_enabled = "no"
    module_jsonrpc_enabled = "no"
    module_mbedtls_enabled = "no"
    module_mobile_vr_enabled = "no"
    module_opensimplex_enabled = "no"
    module_opus_enabled = "no"
    module_pvr_enabled = "no"
    module_recast_enabled = "no"
    module_regex_enabled = "no"
    module_squish_enabled = "no"
    module_svg_enabled = "no"
    module_tga_enabled = "no"
    module_theora_enabled = "no"
    module_tinyexr_enabled = "no"
    module_upnp_enabled = "no"
    module_vhacd_enabled = "no"
    module_vorbis_enabled = "no"
    module_webm_enabled = "no"
    module_webrtc_enabled = "no"
    module_websocket_enabled = "no"
    module_xatlas_unwrap_enabled = "no"

.. seealso::

    :ref:`doc_overriding_build_options`.