React performance in 2025 is becoming increasingly common in day-to-day development. This article offers a systematic look at its usage, inner workings, and optimization strategies.

Core Principles

Let's start by looking at the basic implementation:

import { useState, useEffect, useCallback, useMemo } from "react";

function useDataFetching(url) {
  const [data, setData] = useState(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState(null);

  const fetchData = useCallback(async () => {
    try {
      setLoading(true);
      const res = await fetch(url);
      if (!res.ok) throw new Error(`HTTP error! status: ${res.status}`);
      const json = await res.json();
      setData(json);
    } catch (err) {
      setError(err.message);
    } finally {
      setLoading(false);
    }
  }, [url]);

  useEffect(() => {
    fetchData();
  }, [fetchData]);
  return { data, loading, error, refetch: fetchData };
}

This snippet illustrates the fundamental usage. In real projects you'll also need to account for error handling and edge cases.

Advanced Features

Building on this foundation, we can further optimize:

const observer = new PerformanceObserver((list) => {
  for (const entry of list.getEntries()) {
    if (entry.entryType === "largest-contentful-paint") {
      reportMetric("LCP", entry.startTime);
    }
    if (entry.entryType === "first-input") {
      reportMetric("FID", entry.processingStart - entry.startTime);
    }
  }
});
observer.observe({ entryTypes: ["largest-contentful-paint", "first-input"] });

This approach improves both the testability and scalability of the code.

Project Practice

In a real project, the usage gets a bit more complex:

import { useRef, useEffect, useState } from "react";

function useIntersectionObserver(options = {}) {
  const [isVisible, setIsVisible] = useState(false);
  const ref = useRef(null);

  useEffect(() => {
    const observer = new IntersectionObserver(
      ([entry]) => {
        setIsVisible(entry.isIntersecting);
      },
      { threshold: 0.1, ...options },
    );
    const el = ref.current;
    if (el) observer.observe(el);
    return () => {
      if (el) observer.unobserve(el);
    };
  }, []);

  return [ref, isVisible];
}

Pay attention to edge-case handling—this is crucial in production environments.

Best Practices

Here is a complete example:

import { useReducer, useCallback } from "react";

const initialState = { items: [], filter: "", sort: "date" };

function reducer(state, action) {
  switch (action.type) {
    case "SET_ITEMS":
      return { ...state, items: action.payload };
    case "SET_FILTER":
      return { ...state, filter: action.payload };
    case "ADD_ITEM":
      return { ...state, items: [...state.items, action.payload] };
    case "REMOVE_ITEM":
      return {
        ...state,
        items: state.items.filter((i) => i.id !== action.payload),
      };
    default:
      throw new Error(`Unknown: ${action.type}`);
  }
}

Performance optimization must be tailored to specific scenarios—not every situation calls for aggressive optimization.

Summary

• Always verify compatibility before using in production
• In team collaboration, conventions and documentation matter more than the technology itself
• Stay up-to-date with community trends; technical solutions require continuous iteration