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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Common Performance Problems</title>
<link href="https://fonts.googleapis.com/css2?family=Sora:wght@300;400;600;700;800&family=Space+Mono:wght@400;700&family=Fira+Code:wght@400;600&display=swap" rel="stylesheet">
<style>
:root {
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--c3b:rgba(255,167,38,.06);--c3d:rgba(255,167,38,.18);
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/* Why + Example side by side */
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@media(max-width:700px){.prob-cols{grid-template-columns:1fr;}}
.prob-why{border-radius:14px;padding:18px 20px;}
.prob-why-label{font-family:'Space Mono',monospace;font-size:10px;letter-spacing:1.8px;text-transform:uppercase;margin-bottom:10px;font-weight:700;}
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.prob-impact strong{color:var(--tp);}
/* ── Color per problem ── */
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.p2 .prob-accent{background:var(--c2)}.p2 .prob-num{background:var(--c2)}.p2 .prob-header h2{color:var(--c2)}.p2 .prob-meaning{border-color:var(--c2);background:var(--c2b)}.p2 .prob-why{background:var(--c2b);border:1px solid var(--c2d)}.p2 .prob-why-label{color:var(--c2)}.p2 .pw-tag{background:rgba(255,112,67,.08);border:1px solid var(--c2d);color:var(--c2)}.p2 .prob-ex{background:var(--c2b);border:1px solid var(--c2d)}.p2 .prob-ex-label{color:var(--c2)}.p2 .pem-badge{background:rgba(255,112,67,.12);color:var(--c2)}.p2:hover{box-shadow:0 0 40px rgba(255,112,67,.06);}
.p3 .prob-accent{background:var(--c3)}.p3 .prob-num{background:var(--c3)}.p3 .prob-header h2{color:var(--c3)}.p3 .prob-meaning{border-color:var(--c3);background:var(--c3b)}.p3 .prob-why{background:var(--c3b);border:1px solid var(--c3d)}.p3 .prob-why-label{color:var(--c3)}.p3 .pw-tag{background:rgba(255,167,38,.08);border:1px solid var(--c3d);color:var(--c3)}.p3 .prob-ex{background:var(--c3b);border:1px solid var(--c3d)}.p3 .prob-ex-label{color:var(--c3)}.p3 .pem-badge{background:rgba(255,167,38,.12);color:var(--c3)}.p3:hover{box-shadow:0 0 40px rgba(255,167,38,.06);}
.p4 .prob-accent{background:var(--c4)}.p4 .prob-num{background:var(--c4);color:#1a1a1a}.p4 .prob-header h2{color:var(--c4)}.p4 .prob-meaning{border-color:var(--c4);background:var(--c4b)}.p4 .prob-why{background:var(--c4b);border:1px solid var(--c4d)}.p4 .prob-why-label{color:var(--c4)}.p4 .pw-tag{background:rgba(255,202,40,.06);border:1px solid var(--c4d);color:var(--c4)}.p4 .prob-ex{background:var(--c4b);border:1px solid var(--c4d)}.p4 .prob-ex-label{color:var(--c4)}.p4 .pem-badge{background:rgba(255,202,40,.1);color:var(--c4)}.p4:hover{box-shadow:0 0 40px rgba(255,202,40,.05);}
.p5 .prob-accent{background:var(--c5)}.p5 .prob-num{background:var(--c5)}.p5 .prob-header h2{color:var(--c5)}.p5 .prob-meaning{border-color:var(--c5);background:var(--c5b)}.p5 .prob-why{background:var(--c5b);border:1px solid var(--c5d)}.p5 .prob-why-label{color:var(--c5)}.p5 .pw-tag{background:rgba(102,187,106,.08);border:1px solid var(--c5d);color:var(--c5)}.p5 .prob-ex{background:var(--c5b);border:1px solid var(--c5d)}.p5 .prob-ex-label{color:var(--c5)}.p5 .pem-badge{background:rgba(102,187,106,.12);color:var(--c5)}.p5:hover{box-shadow:0 0 40px rgba(102,187,106,.06);}
.p6 .prob-accent{background:var(--c6)}.p6 .prob-num{background:var(--c6)}.p6 .prob-header h2{color:var(--c6)}.p6 .prob-meaning{border-color:var(--c6);background:var(--c6b)}.p6 .prob-why{background:var(--c6b);border:1px solid var(--c6d)}.p6 .prob-why-label{color:var(--c6)}.p6 .pw-tag{background:rgba(66,165,245,.08);border:1px solid var(--c6d);color:var(--c6)}.p6 .prob-ex{background:var(--c6b);border:1px solid var(--c6d)}.p6 .prob-ex-label{color:var(--c6)}.p6 .pem-badge{background:rgba(66,165,245,.12);color:var(--c6)}.p6:hover{box-shadow:0 0 40px rgba(66,165,245,.06);}
.p7 .prob-accent{background:var(--c7)}.p7 .prob-num{background:var(--c7)}.p7 .prob-header h2{color:var(--c7)}.p7 .prob-meaning{border-color:var(--c7);background:var(--c7b)}.p7 .prob-why{background:var(--c7b);border:1px solid var(--c7d)}.p7 .prob-why-label{color:var(--c7)}.p7 .pw-tag{background:rgba(171,71,188,.08);border:1px solid var(--c7d);color:var(--c7)}.p7 .prob-ex{background:var(--c7b);border:1px solid var(--c7d)}.p7 .prob-ex-label{color:var(--c7)}.p7 .pem-badge{background:rgba(171,71,188,.12);color:var(--c7)}.p7:hover{box-shadow:0 0 40px rgba(171,71,188,.06);}
/* ═══ SUMMARY TABLE ═══ */
.sum-head{display:flex;align-items:center;gap:14px;margin:52px 0 22px;}
.sum-head .sh-icon{font-family:'Space Mono',monospace;font-size:13px;font-weight:700;color:var(--bg);background:var(--c6);width:36px;height:36px;border-radius:10px;display:flex;align-items:center;justify-content:center;}
.sum-head h2{font-size:24px;font-weight:700;}
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tbody tr{background:var(--bg-card);}tbody tr:nth-child(even){background:var(--bg-alt);}
tbody td{padding:12px 16px;border-bottom:1px solid var(--border);color:var(--ts);line-height:1.55;vertical-align:top;}
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</head>
<body>
<div class="bg-grid"></div>
<div class="bg-blob a"></div>
<div class="bg-blob b"></div>
<div class="bg-blob c"></div>
<div class="page">
<!-- HERO -->
<div class="hero">
<div class="hero-badge">Problems · Performance Testing 101</div>
<h1>Common Performance Problems</h1>
<p class="hero-sub">
The <strong>7 most frequent performance issues</strong> encountered during testing and in production — what they mean, why they happen, and how they manifest.
</p>
<div class="hero-count">
<span class="hc-dot" style="background:var(--c1)"></span>
<span class="hc-dot" style="background:var(--c2)"></span>
<span class="hc-dot" style="background:var(--c3)"></span>
<span class="hc-dot" style="background:var(--c4)"></span>
<span class="hc-dot" style="background:var(--c5)"></span>
<span class="hc-dot" style="background:var(--c6)"></span>
<span class="hc-dot" style="background:var(--c7)"></span>
7 Problems Every Tester Must Know
</div>
</div>
<!-- ═══ 1. REDUCED THROUGHPUT ═══ -->
<div class="prob p1">
<div class="prob-header">
<div class="prob-num">01</div>
<h2>Reduced Throughput</h2>
<span class="prob-icon">📉</span>
</div>
<div class="prob-body">
<div class="prob-meaning" style="border-color:var(--c1);background:var(--c1b);">
The system is processing <strong>fewer requests/transactions per second</strong> than expected. Users experience delays as the system cannot handle incoming traffic fast enough.
</div>
<div class="prob-cols">
<div class="prob-why">
<div class="prob-why-label">Why It Happens</div>
<div class="prob-why-tags">
<span class="pw-tag">Slow Backend Calls</span>
<span class="pw-tag">Database Slowness</span>
<span class="pw-tag">Insufficient CPU</span>
<span class="pw-tag">Poorly Written Code</span>
<span class="pw-tag">Network Bottlenecks</span>
</div>
</div>
<div class="prob-ex">
<div class="prob-ex-label">Example</div>
<div class="prob-ex-metric">
<span class="pem-badge">EXPECTED</span>
<span class="pem-text"><strong>100 req/sec</strong></span>
<span class="pem-arrow">→</span>
<span class="pem-badge" style="background:rgba(255,82,82,.2);">ACTUAL</span>
<span class="pem-text"><strong>40 req/sec</strong></span>
</div>
</div>
</div>
</div>
</div>
<!-- ═══ 2. POOR RESPONSE TIME ═══ -->
<div class="prob p2">
<div class="prob-header">
<div class="prob-num">02</div>
<h2>Poor Response Time</h2>
<span class="prob-icon">🐌</span>
</div>
<div class="prob-body">
<div class="prob-meaning" style="border-color:var(--c2);background:var(--c2b);">
Each request takes <strong>too long to return a response</strong>. The delay is felt directly by end users as sluggish interactions.
</div>
<div class="prob-cols">
<div class="prob-why">
<div class="prob-why-label">Why It Happens</div>
<div class="prob-why-tags">
<span class="pw-tag">Heavy Server Processing</span>
<span class="pw-tag">Slow DB Queries</span>
<span class="pw-tag">High Network Latency</span>
<span class="pw-tag">Thread Pool Saturation</span>
</div>
</div>
<div class="prob-ex">
<div class="prob-ex-label">Example</div>
<div class="prob-ex-metric">
<span class="pem-badge">SLA</span>
<span class="pem-text">Login API: <strong>200 ms</strong></span>
<span class="pem-arrow">→</span>
<span class="pem-badge" style="background:rgba(255,112,67,.2);">ACTUAL</span>
<span class="pem-text"><strong>2,000 ms</strong></span>
</div>
<div class="prob-impact"><strong>10× slower</strong> than expected — users abandon the page.</div>
</div>
</div>
</div>
</div>
<!-- ═══ 3. LACK OF SCALABILITY ═══ -->
<div class="prob p3">
<div class="prob-header">
<div class="prob-num">03</div>
<h2>Lack of Scalability</h2>
<span class="prob-icon">📊</span>
</div>
<div class="prob-body">
<div class="prob-meaning" style="border-color:var(--c3);background:var(--c3b);">
Performance <strong>does not increase</strong> when more resources (CPU / RAM / instances) are added. Throwing hardware at the problem doesn't fix it.
</div>
<div class="prob-cols">
<div class="prob-why">
<div class="prob-why-label">Why It Happens</div>
<div class="prob-why-tags">
<span class="pw-tag">Architecture Limitations</span>
<span class="pw-tag">Single-Threaded Processes</span>
<span class="pw-tag">DB Bottlenecks</span>
<span class="pw-tag">Global Locks</span>
</div>
</div>
<div class="prob-ex">
<div class="prob-ex-label">Example</div>
<div class="prob-ex-metric">
<span class="pem-badge">ACTION</span>
<span class="pem-text">Servers: <strong>2 → 4</strong> instances</span>
</div>
<div class="prob-ex-metric">
<span class="pem-badge" style="background:rgba(255,167,38,.2);">RESULT</span>
<span class="pem-text">Throughput <strong>barely increases</strong></span>
</div>
</div>
</div>
</div>
</div>
<!-- ═══ 4. SERVER USER LIMIT ═══ -->
<div class="prob p4">
<div class="prob-header">
<div class="prob-num">04</div>
<h2>Server Can't Handle X Users</h2>
<span class="prob-icon">💥</span>
</div>
<div class="prob-body">
<div class="prob-meaning" style="border-color:var(--c4);background:var(--c4b);">
The application <strong>crashes, hangs, or becomes slow</strong> when user count crosses a certain limit.
</div>
<div class="prob-cols">
<div class="prob-why">
<div class="prob-why-label">Why It Happens</div>
<div class="prob-why-tags">
<span class="pw-tag">CPU Spikes to 100%</span>
<span class="pw-tag">Memory Exhaustion</span>
<span class="pw-tag">Thread Pool Full</span>
<span class="pw-tag">DB Pool Maxed Out</span>
</div>
</div>
<div class="prob-ex">
<div class="prob-ex-label">Example</div>
<div class="prob-ex-metric">
<span class="pem-badge">STABLE</span>
<span class="pem-text">Up to <strong>500 users</strong> ✓</span>
</div>
<div class="prob-ex-metric">
<span class="pem-badge" style="background:rgba(255,202,40,.18);">FAILS</span>
<span class="pem-text">At <strong>600+ users</strong> — unstable</span>
</div>
</div>
</div>
</div>
</div>
<!-- ═══ 5. HEAP PROBLEM ═══ -->
<div class="prob p5">
<div class="prob-header">
<div class="prob-num">05</div>
<h2>Heap Problem</h2>
<span class="prob-icon">🧠</span>
</div>
<div class="prob-body">
<div class="prob-meaning" style="border-color:var(--c5);background:var(--c5b);">
Java heap memory is not managed well → leads to <strong>OutOfMemoryError</strong>, long GC pauses, or memory leaks. Memory keeps increasing and never comes down.
</div>
<div class="prob-cols">
<div class="prob-why">
<div class="prob-why-label">Symptoms</div>
<div class="prob-why-tags">
<span class="pw-tag">Memory Never Reclaimed</span>
<span class="pw-tag">Frequent Full GC</span>
<span class="pw-tag">GC Pause Times ↑</span>
<span class="pw-tag">OutOfMemoryError</span>
</div>
</div>
<div class="prob-ex">
<div class="prob-ex-label">Example</div>
<div class="prob-ex-metric">
<span class="pem-badge">UNDER LOAD</span>
<span class="pem-text">Heap usage → <strong>100%</strong></span>
</div>
<div class="prob-impact"><strong>Very slow responses</strong> → eventual application crash.</div>
</div>
</div>
</div>
</div>
<!-- ═══ 6. THREAD POOL ISSUE ═══ -->
<div class="prob p6">
<div class="prob-header">
<div class="prob-num">06</div>
<h2>Thread Pool Issue</h2>
<span class="prob-icon">🧵</span>
</div>
<div class="prob-body">
<div class="prob-meaning" style="border-color:var(--c6);background:var(--c6b);">
All available threads are occupied → new requests <strong>wait in queue or get rejected</strong>. The server is alive but unable to process more work.
</div>
<div class="prob-cols">
<div class="prob-why">
<div class="prob-why-label">Why It Happens</div>
<div class="prob-why-tags">
<span class="pw-tag">Slow Backend Calls</span>
<span class="pw-tag">Blocking I/O</span>
<span class="pw-tag">Small Thread Pool Size</span>
</div>
</div>
<div class="prob-ex">
<div class="prob-ex-label">Example</div>
<div class="prob-ex-metric">
<span class="pem-badge">POOL</span>
<span class="pem-text"><strong>50</strong> threads</span>
<span class="pem-arrow">←</span>
<span class="pem-badge" style="background:rgba(66,165,245,.2);">INCOMING</span>
<span class="pem-text"><strong>200</strong> requests</span>
</div>
<div class="prob-impact"><strong>150 requests wait</strong> → high response time → 503 Service Unavailable errors.</div>
</div>
</div>
</div>
</div>
<!-- ═══ 7. LONG DB QUERIES ═══ -->
<div class="prob p7">
<div class="prob-header">
<div class="prob-num">07</div>
<h2>Long Running DB Queries</h2>
<span class="prob-icon">🗄️</span>
</div>
<div class="prob-body">
<div class="prob-meaning" style="border-color:var(--c7);background:var(--c7b);">
Queries take too much time due to <strong>poor SQL design or missing indexes</strong>. This bottleneck cascades and slows down the entire application.
</div>
<div class="prob-cols">
<div class="prob-why">
<div class="prob-why-label">Why It Happens</div>
<div class="prob-why-tags">
<span class="pw-tag">Missing Indexes</span>
<span class="pw-tag">Large Data Scans</span>
<span class="pw-tag">Complex Joins</span>
<span class="pw-tag">Query Locks</span>
<span class="pw-tag">High DB CPU</span>
</div>
</div>
<div class="prob-ex">
<div class="prob-ex-label">Example</div>
<div class="prob-ex-metric">
<span class="pem-badge">NORMAL</span>
<span class="pem-text">"Get User Orders": <strong>50 ms</strong></span>
</div>
<div class="prob-ex-metric">
<span class="pem-badge" style="background:rgba(171,71,188,.2);">UNDER LOAD</span>
<span class="pem-text"><strong>3,000 ms</strong> (table scan + lock contention)</span>
</div>
<div class="prob-impact"><strong>60× slower</strong> → entire application bottlenecked.</div>
</div>
</div>
</div>
</div>
<!-- ═══ SUMMARY TABLE ═══ -->
<div class="sum-head">
<div class="sh-icon">∑</div>
<h2>Quick Reference Summary</h2>
</div>
<div class="sum-wrap">
<table>
<thead><tr><th>Problem</th><th>Meaning</th><th>Example</th></tr></thead>
<tbody>
<tr><td><span class="dot d1"></span>Reduced Throughput</td><td>System handles fewer req/sec</td><td>Expected 100 TPS → actual 40 TPS</td></tr>
<tr><td><span class="dot d2"></span>Poor Response Time</td><td>Requests take longer to complete</td><td>Login: 2 sec instead of 200 ms</td></tr>
<tr><td><span class="dot d3"></span>Lack of Scalability</td><td>More resources ≠ better performance</td><td>+= servers but same TPS</td></tr>
<tr><td><span class="dot d4"></span>Server User Limit</td><td>Crashes/slow at certain user count</td><td>Stable till 500, fails at 600</td></tr>
<tr><td><span class="dot d5"></span>Heap Problem</td><td>Memory leak / GC issues</td><td>Heap 100%, app slows or crashes</td></tr>
<tr><td><span class="dot d6"></span>Thread Pool Issue</td><td>No free threads → requests wait</td><td>Pool: 50; Incoming: 200 requests</td></tr>
<tr><td><span class="dot d7"></span>Long DB Queries</td><td>Slow SQL → delays entire app</td><td>Query: 3 sec instead of 50 ms</td></tr>
</tbody>
</table>
</div>
<!-- FOOTER -->
<div class="footer">
<p><span class="fa">PERFORMANCE TESTING PROBLEMS</span> · Detect Early · Diagnose Fast · Fix Right · Author: Angshuman Basak</p>
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