Performance pass for reflection, expression, and metadata hotspots

[msLoginoff]

Review runtime hotspots before optimizing.

Candidates:

• replace repeated PropertyInfo.GetValue with compiled getter caches
• replace MethodInfo.Invoke in the generic loader with cached delegates
• review EF metadata lookup caching
• measure impact before changing behavior
• preserve batching and pipeline clarity

This should be benchmark-driven, not a speculative rewrite.

[msLoginoff]

Related follow-up: #14 tracks explicit enrichment load diagnostics for batching, tracked-entity reuse, key counts, include paths, and SQL-load counts. This should support the benchmark-driven performance work here without changing the broader scope of this issue.