I noticed that building the tests under the install-all-meta target takes a very long time to complete. Some of that time is due to linking, but an even greater portion appears to be SCons scanning its cache for dependencies of unittests.txt and integration-tests.txt (among others?). What we have essentially done is to pin every object file node as a dependency to a single SCons node that then outputs a single text file for each test class.

This is probably not what we really wanted to do if we care about performance. We should rearrange this so these text files get appended to atomically somehow as part of the test build, or potentially some other way that accomplishes the same thing without involving the SCons dependency graph.