Gerbview is very slow

[SFEN]

Using the latest version of gerbview, it takes a really, really, long time to open complex gerber files.

For specific reference, we can use the following reference board:

https://www.intel.com/content/dam/altera-www/global/en_US/support/boards-kits/stratix10/soc/stratix10SX_1sx280uf50_soc_revB_v18.0b219_v1.0.zip

Opening just the FAB2.art layer takes less than 3s using the free version of allegro. But it takes over a minute using gerbview. This makes reviewing entire designs for complex boards impossible.

Application: GerbView
Version: (5.99.0-311-g81ce588a0), release build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.61.1 OpenSSL/1.1.1 zlib/1.2.11 libidn2/2.0.5 libpsl/0.20.2 (+libidn2/2.0.4) libssh2/1.8.0 nghttp2/1.33.0
Platform: Linux 4.18.12-arch1-1-ARCH x86_64, 64 bit, Little endian, wxGTK
Build Info:
    Build date: Nov 5 2019 22:09:14
    wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
    Boost: 1.68.0
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.61.1
    Compiler: GCC 8.2.1 with C++ ABI 1013

Build settings:
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=OFF
    KICAD_SCRIPTING_WXPYTHON=OFF
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON