Reduce memory footprint

When drawing paths, the immutable approach to drawn objects regularly consumes more heap memory than the default maximum 64MB defined by the Gradle wrapper. Of course, using a larger heap is an option, but perhaps we could optimize this, ideally without compromising on immutability?

Start by examining the path-drawing code and how drawn objects are represented immutably; reproduce the heap usage under the Gradle wrapper's 64MB limit. Done means reducing memory consumption during drawing without compromising immutability, with evidence that the issue no longer regularly exceeds the limit.

Written by the indexing model from the issue text.