The SVG produced by MathJax is a bit verbose. It is possible to reduce the size using tools like scour (apt-get install python-scour):
scour --indent=none --shorten-ids -i /tmp/test.svg -o /tmp/test.scoured.svg
ls -lh /tmp/test*
-rw-r--r-- 1 gabriel gabriel 20K Oct 26 21:42 /tmp/test.svg
-rw-r--r-- 1 gabriel gabriel 15K Oct 26 22:05 /tmp/test.scoured.svg
After gzip -9 on each of the SVG files:
-rw-r--r-- 1 gabriel gabriel 7.3K Oct 26 21:57 /tmp/test.svg.gz
-rw-r--r-- 1 gabriel gabriel 5.5K Oct 26 22:05 /tmp/test.scoured.svg.gz
So about a 25% reduction of the compressed size, I believe without any quality loss.
There is a partial port of scour to JS (https://github.com/preciousforever/SVG-Cleaner), but it does miss the crucial path simplification pass from scour.
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