Unoptimized still makes them 25% faster:

+-------------------+-----------------+------------------------------+
| Benchmark         | 37_bench_tracer | 37_bench_tracer_first_cython |
+===================+=================+==============================+
| trivial tracer    | 792 ns          | 786 ns: 1.01x faster (-1%)   |
+-------------------+-----------------+------------------------------+
| monitor tracer    | 1.62 us         | 1.24 us: 1.31x faster (-24%) |
+-------------------+-----------------+------------------------------+
| max switch tracer | 3.06 us         | 1.89 us: 1.62x faster (-38%) |
+-------------------+-----------------+------------------------------+
| hub switch tracer | 2.16 us         | 1.68 us: 1.29x faster (-22%) |
+-------------------+-----------------+------------------------------+