The slow startup of Drawing was being caused by a “broken” regular expression, which was causing the text search it was used in to try using up too much of one resource or another (eg: stack space) and throw an exception (after ~20 seconds on my machine). There was a try/catch around that particular chunk of code, which essentially just kept the program quietly running.
Anyways, to get it going again I changed:
// Regex e1 attempts to find: //  - A text tag that contains "freecad:editable=", and it's matching tspan tag //  - positive integer font size in px //  - pos/neg float x coordinate //  - pos/neg float y coordinate //  - one or more character Perl "word" for freecad:editable value ... "<text.*?font-size:([\\d]+)px.*?x=\"([\\d.-]+)\".*?y=\"([\\d.-]+)\".*?freecad:editable=\"(\\w+)\".*?>.*?<tspan.*?"
Now, we get a much faster load, and the beginnings of another working feature! Now, we’ve got editable text boxes for the title, author, scale, etc. as encoded in the drawing templates. Of course, all this will require a fair bit more work before it’s ready to go…