Caching versus pre-rendering

Caching versus pre-rendering

Overview

Content displayed in rendering portlets and through IBM Web Content Manager can be cached. An alternative to caching is the use of the pre-rendering feature. View the differences between each strategy.
A pre-rendered site can be viewed in two ways:

Use a web server Similar to using basic caching because the displayed content is static and custom caching cannot be used.
Web Content Manager Similar to using advanced caching because content can be dynamic and custom caching can be used.

Basic caching versus a pre-rendered site delivered with a web server
At first glance, the pre-rendering feature and basic caching do the same thing. There are however, some major differences that will determine which feature is the best for you.
The main difference between the two features is that the pre-rendering feature takes a snapshot of the entire site each time it is run. Basic caching only caches on a page-by-page basis. If performance is main issue, then pre-rendering might be the answer. If not, then basic caching might be a better option.

Function Basic caching Pre-rendered site delivered with a web server
Performance Very fast Extremely fast
Connect tag processing No No
Custom caching No No
Memory requirements Low to Medium Memory requirements depends on the web server being used.
Disk requirements Low to Medium Potentially very high as the entire site must be able to fit on disk.
Unexpected broken links Yes
As some pages may be cached at different times, there is a small chance that not all the links on a cached page will be currently valid.
No
The site is pre-rendered in a single batch, greatly reducing the chances of inconsistencies in the site.

Advanced caching versus a pre-rendered site delivered using Web Content Manager
These options are very similar. You may have to test both strategies before deciding which is best for site.

Function Advanced caching Pre-rendered site delivered through WCM
Performance Fast when cached, but slower if the requested page has expired from the cache. (As tag processing has a cost, this depends on how many connect tags a page contains.) Fast, but as tag processing has a cost, this depends on how many connect tags a page contains.
Connect tag processing Yes No
Custom caching Yes No
Memory requirements Medium to high. Medium to high.
Disk requirements Medium to high. Medium to high.
Unexpected broken links Yes
As some pages may be cached at different times, there is a small chance that not all the links on a cached page will be currently valid.
No
The site is pre-rendered in a single batch, greatly reducing the chances of inconsistencies in the site.

Parent
Caching options

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Use a web server	Similar to using basic caching because the displayed content is static and custom caching cannot be used.
Web Content Manager	Similar to using advanced caching because content can be dynamic and custom caching can be used.

Function	Basic caching	Pre-rendered site delivered with a web server
Performance	Very fast	Extremely fast
Connect tag processing	No	No
Custom caching	No	No
Memory requirements	Low to Medium	Memory requirements depends on the web server being used.
Disk requirements	Low to Medium	Potentially very high as the entire site must be able to fit on disk.
Unexpected broken links	Yes As some pages may be cached at different times, there is a small chance that not all the links on a cached page will be currently valid.	No The site is pre-rendered in a single batch, greatly reducing the chances of inconsistencies in the site.

Function	Advanced caching	Pre-rendered site delivered through WCM
Performance	Fast when cached, but slower if the requested page has expired from the cache. (As tag processing has a cost, this depends on how many connect tags a page contains.)	Fast, but as tag processing has a cost, this depends on how many connect tags a page contains.
Connect tag processing	Yes	No
Custom caching	Yes	No
Memory requirements	Medium to high.	Medium to high.
Disk requirements	Medium to high.	Medium to high.
Unexpected broken links	Yes As some pages may be cached at different times, there is a small chance that not all the links on a cached page will be currently valid.	No The site is pre-rendered in a single batch, greatly reducing the chances of inconsistencies in the site.