Perf improvements when adding metrics

[bdeitte]

A small list (after some rechecking on things) of perf improvements to make

[Copilot]

Pull request overview

This PR introduces several CPU performance optimizations for hot-shots, a Node.js client for StatsD, DogStatsD, and Telegraf. The changes focus on reducing redundant string operations, object allocations, and function calls in hot paths when sending metrics.

Changes:

• Pre-join global tags into a cached string to avoid repeated string concatenation and joining operations
• Optimize overrideTags helper with a fast path that concatenates arrays when tags don't overlap
• Replace process.hrtime() with process.hrtime.bigint() for simpler, more efficient timing calculations
• Eliminate unnecessary Buffer.from() conversions for TCP/STREAM protocols
• Cache and reuse Buffer.byteLength calculations

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
lib/transport.js	Refactored addEol to use early return and handle string inputs directly
lib/statsd.js	Added _globalTagStr cache for pre-joined global tags, optimized Buffer handling for TCP/STREAM, reused messageBytes variable
lib/statsFunctions.js	Replaced process.hrtime() array operations with process.hrtime.bigint() for simpler time delta calculations
lib/helpers.js	Implemented fast path in overrideTags to avoid expensive filtering when tags don't overlap, switched from plain object to Map for better performance
CHANGES.md	Documented the performance improvements in the changelog

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