FreeMarker vs. GSP for Dynamic Template Rendering

I find out that there are two ways in Grails to render dynamic template (String template), using FreeMarker and GSP. FreeMarker support enabled by freemarker plugin and freemarker-tags plugin. Special thanks to Jeff and Daniel creating these plugins, it will be less options for Grails view technology without their contribution. Given two options, I need to perform some micro-benchmarking to find out which one is the appropriate technology for given requirements.


The Objective
To evaluate and decide which template engine (FreeMarker or GSP) to use as Form Template of the Grails Form Builder Plugin.


The Result
FreeMarker is the winner. By perform rendering 100 times for the same template, GSP need 119,946ms and FreeMarker need approximately 1/4 of GSP, 32,749ms (Surprise? Yes, I am surprised about the performance of FreeMarker over GSP in dynamic template rendering).


How I Did It 
The Benchmark Case
The dynamic template was created based on the following domain class:
package test_freemarker2

class Test1 {
    int prop1
    String prop2
    Date prop3
   
    static constraints = { prop2 blank:false }
}

The FreeMarker's template rendering code:
new Template("freemarkerTemplate",
             new StringReader(freemarkerTemplateCode),
             freemarkerConfig.configuration)
            .process([test1Instance: test1Instance, flash:flash], out)

The GSP's template rendering code:
groovyPagesTemplateEngine.createTemplate(gspTemplateCode, 'gspTemplate').make([test1Instance: test1Instance]).writeTo(out)

As the template code (freemarkerTemplateCode and gspTemplateCode) was too lengthy, I will not describe it here (You can download the complete source code of the application here to run the benchmark test in your own environment).

The Benchmark Application
I run the benchmarking tests with the following steps:

1. Start the application using grails run-war.
2. After the application was started, open or refresh the URL http://localhost:8080/freemarker-vs-gsp/benchmark/index in your browser. You will see the following screen:
   
   
3. Click on "FreeMarker" link and wait for test completion and shutdown the application. Do the same for "GSP", start from step 1.

The Environment
Operating System: Puppy Linux 4.3.1
JDK:  1.6.0_20
Grails: 1.3.6
Processor: Intel Pentium M 1.5GHz
Memory: 1285MB

The Source Code
You can download the complete source code of the application and run it yourself.

Conclusion
Even the winner of this benchmark test is FreeMarker, the benchmark code was written based on my limited knowledge of FreeMarker and GSP. You may have better way to write optimized code than I do, please let's me know if you found a better way.

Edited on 28 Jun 2012: Please see the part 2 of this post.