tracing: revisit perf implication of many trace tags

We have an increasing amount of trace tags that we emit without any configuration. We should try to profile the cost of doing these tags, especially if there is no tracing configured (null tracer). We should potentially allow for the emitted tags to be configured in high perf scenarios.

Start by locating the code that emits trace tags and the null-tracer path, then profile tag handling with tracing disabled. Done means documenting the performance cost and determining whether configurable emitted tags are needed for high-performance scenarios.

Written by the indexing model from the issue text.