But most people think of cache only as a WordPress plugin. In reality, the biggest performance gains come from server-side cache.

In this article you will clearly learn:

• What is cache?
• What are the types of server-side cache?
• What is the difference between LiteSpeed, Redis, and Varnish?
• What questions should you ask your hosting provider?

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1. What Is Cache? (Brief Explanation)

Cache means storing a pre-built copy of a dynamically generated page and serving it to users instead of regenerating it every time.

Normal process (without cache):

User → WordPress → PHP → MySQL → Server → Response

With cache:

User → Cache → Response

That is why cache:

• reduces CPU usage
• reduces database load
• reduces TTFB
• reduces LCP
• lets you handle more concurrent visitors

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2. Cache Types (The Most Important Section)

There are multiple cache layers on the server side:

Cache Type	What It Does	Impact
Page Cache	Caches the entire page	Very high
Object Cache	Caches database queries	High
Opcode Cache	Caches PHP code	Medium
Browser Cache	Cache in the user's browser	Medium
CDN Cache	Caches static files	High

The three most important:

• Page Cache
• Object Cache
• Opcode Cache

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3. What Is Page Cache?

This is where the biggest performance gain occurs.

WordPress normally does the following for every visitor:

• runs PHP
• executes a database query
• builds the page

With page cache:

• a ready-made HTML file is delivered directly

Result:

Situation	TTFB
No cache	400–800 ms
Page cache on	50–150 ms

Page cache technologies:

• LiteSpeed Cache
• Nginx FastCGI Cache
• Varnish Cache

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4. What Is Object Cache? (Redis / Memcached)

Object cache caches database queries.

Examples:

• Product information
• Menus
• Settings
• User data

Instead of being fetched from MySQL every time, this data is kept in RAM.

Common systems:

• Redis
• Memcached

It makes a particularly noticeable difference on:

• WooCommerce
• Large blogs
• Membership systems
• LMS
• SaaS applications

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5. What Is Opcode Cache? (OPcache)

PHP files are compiled every time they run. OPcache keeps the compiled PHP code in RAM and prevents it from being recompiled.

This also:

• reduces CPU usage
• speeds up PHP
• reduces TTFB

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6. LiteSpeed vs Nginx vs Varnish

System	Cache Type	Advantage
LiteSpeed	Page Cache	Highly compatible with WordPress
Nginx	FastCGI Cache	Event-driven, fast
Varnish	Reverse Proxy Cache	Ideal for high-traffic sites
Redis	Object Cache	Speeds up the database
Memcached	Object Cache	Speeds up the database

Recommended combinations:

LiteSpeed + Redis + OPcache
or
Nginx + FastCGI Cache + Redis + OPcache

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7. Questions to Ask Your Hosting Provider

Always ask these when choosing a hosting plan:

Question	Why
Is there page cache?	The biggest speed impact
LiteSpeed or Nginx?	Server infrastructure
Is Redis supported?	Object cache
Is OPcache active?	PHP performance
Is Varnish available?	High traffic
Is the cache stored in RAM?	Disk cache can be slow

Minimum ideal setup:

Page Cache + Redis + OPcache

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8. What Happens Without Cache?

Situation	Result
No cache	High CPU usage
No cache	High TTFB
No cache	Low concurrent user capacity
No cache	Poor Core Web Vitals

Many sites are slow simply because there is no cache.

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9. Real-World Performance Difference

System	TTFB	Concurrent Visitors
No cache	600 ms	20
Page Cache only	120 ms	200
Page Cache + Redis	80 ms	400
Page Cache + Redis + CDN	50 ms	1000+

Cache multiplies capacity.

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10. Summary

Technology	Impact
Page Cache	Very high
Redis	High
OPcache	Medium
CDN	High
Browser Cache	Medium

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CONCLUSION

The bulk of website performance comes from this trio:

Page Cache + Redis + OPcache

If these three technologies are absent when you choose a hosting plan, your site may be slow no matter how powerful the server is.

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