DrRacket non-responsive after generating complex picts using Rhombus

1. Clone https://github.com/awsalmah/Y390 (at db5af715170ca79d184f190b273de5d29a65058e)
2. Open https://github.com/awsalmah/Y390/blob/db5af715170ca79d184f190b273de5d29a65058e/11.%20ps11/ps11.rhm in DrRacket (tested on Mac and Linux and Windows)
3. Run the file.
4. Run draw_trip(generate_koch(100),turtle(40,100,0),empty_scene(200,200)) in the Interactions window
5. Note that it takes quite a while, and after the image is printed it take a long time for the prompt to appear.
6. DrRacket becomes highly non-responsive (to clicks, it's slow to run subsequent expressions in the Interactions Window) and this persists over time.

A few notes:

1. Similar picts constructed in Racket with 2htdp/image do not have this behavior
2. Minimizing the file to a single Rhombus file with just the relevant pict do not seem to have this behavior.
3. Running the same things in racket-mode in Emacs does not seem to have this behavior.
4. Memory usage becomes very high during this experiment (750 MB -> 1350 MB or more)
5. Closing all tabs with #lang rhombus and clicking the GC button causes memory usage to revert to the previous level.

Start by cloning Y390 at db5af715170ca79d184f190b273de5d29a65058e, opening 11. ps11/ps11.rhm in DrRacket, and reproducing the draw_trip call in the Interactions window. Compare the behavior with the noted 2htdp/image and racket-mode cases, while observing memory usage and responsiveness. Done means identifying and addressing the cause of the slowdown and confirming normal interaction after the expression runs.