Performance improvements across the project

[DavidKorczynski]

Fuzz-introspector has issues with large projects on OSS-Fuzz and Git is an example of this.

When running fuzz-introspector on Git there are two issues:

1. The initial compiling of fuzzers take up a large amount of memory and the process may be killed on smaller machines.
2. The post-processing takes a long time (70+ minutes on my machine) to complete.

The code has so far not had any concerns about performance so it's expected some code will be slow. However, this should be improved.

Somewhat related issue: https://github.com/ossf/fuzz-introspector/issues/3