devot:eeDevoted to ExpressionEngine

Advanced conditionals in the ‘global’ template scope (not within a tag) are generally parsed by the EE template parser near the end of the process. This unfortunately means that any tags within non-matching conditions are parsed first, before being removed. This can have a significant performance impact if the nested tags are doing a lot of processing, such as is the case with the {exp:channel} tag.

One way around this issue is to use embeds, which are parsed after advanced conditionals. Embeds however have their own overhead, as a new instance of the template parser is needed for each one.

Happily we can now force the early parsing of advanced conditionals. Only the matching condition will remain in the template to be parsed. Here are a few examples:

{exp:ifelse parse="inward"}    
    {if member_id == '1' OR group_id == '2'}
        Admin content
    {if:elseif logged_in}
        Member content
    {if:else}
        Public content
    {/if}
{/exp:ifelse}

To preserve {if no results} conditionals inside nested tags, wrap your ‘no results’ content with {no_results}{/no_results}. Example:

{exp:ifelse parse="inward"}    
    {if segment_1 == 'news' AND segment_2 == 'category'}
        News category page
        {exp:channel:entries channel="news"}
            {no_results} 
                No results 
            {/no_results}
        {/exp:channel:entries}
    {if:elseif segment_1 == 'news' AND segment_2 == ''}
         News landing page
    {if:else}
        News story page
    {/if}
{/exp:ifelse}

You can use any of the standard global variables, segment variables, member variables or embedded variables.

Nested tags
This plugin will not parse advanced conditionals *inside* any nested plugin/module tags; these will be left untouched for the parent tag to process.

IfElse cannot currently be nested inside itself due to a flaw in the way the EE template parser works. However, the if/else conditional tags themselves can be nested.