tce-load -i compiletc rust gtk3-dev gtk3-gir gobject-introspection-dev vala-dev perl5 

wget https://ftp.gnome.org/pub/GNOME/sources/librsvg/2.48/librsvg-2.48.9.tar.xz

cd librsvg-2.48.9

edit Cargo.toml
debug = false

CC="gcc -mtune=generic -Os -pipe" CXX="g++ -mtune=generic -Os -pipe -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local --disable-static --localstatedir=/var --enable-vala

[lto enabled in Cargo.toml?]

find . -name Makefile -type f -exec sed -i 's/-g -O2//g' {} \;

make [11m 57.93s]
make install

librsvg 8.9mb vs previous 185kb

librsvg-2.48.9

        prefix:                         /usr/local
        C compiler:                     gcc -mtune=generic -Os -pipe
        rustc:                          rustc 1.42.0

        Cairo version:                  1.16.0
        Pango version:                  1.44.7
        Freetype version:               22.0.16
        Harfbuzz version:               2.7.2

        Debugging information for Rust: no

        Build introspectable bindings:  yes
        Build Vala bindings:            yes
        Build GdkPixbuf loader:         yes
        Build miscellaneous tools:      yes
        Build HTML documentation:       no