Form page caching or DB storage of form text for higher throughput

I just tried this out.... And, I corrected the error in the posted code.

SO, for 5.x here is another version of the subroutine...

function oat_header() {
  global $oatlocus;
  global $g_fieldsetCount;

  if ( $g_fieldsetCount ) {
    $module_path = base_path() . drupal_get_path('module', 'spellcheck');
    drupal_add_js("var gNum_fieldsets = $g_fieldsetCount;", 'inline');
  }
}




function query_form_description($form_id,$form) {
  static $loaded_forms = array();

  if ( count($loaded_forms) == 0 ) {
    // Get the modules to load the forms...
    $loaded_forms = module_invoke_all('registered_forms');
  }

  if ( ( count($loaded_forms) > 0 ) && ( isset($loaded_forms[$form_id]) ) ) {
    return($loaded_forms[$form_id]);
  }

  return(null);
}




function changed_form($form_id,$form) {

  $form_info = query_form_description($form_id,$form);

  if ( $form_info != null ) {
  
    if ( $form_info->dynamic ) {  // if the form is dynamic, it is always changing.
      return(true);
    } else {
      return($form_info->changed);
    }

  }

  return(true); 
}



function fetch_prerendered_form($form_id) {
  $form_info = query_form_description($form_id,$form);
  if ( $form_info != null ) {
    if ( strlen($form_info->substitutions_keys) == 0 ) {
      return($form_info->formtext); // let the modules get it from the DB.
    } else {
      return($form_info); // let the modules get it from the DB.
    }
  }
  return("FORM NOT RENDERED: " . $form_id);
}



function retrieve_form_defaults($form,$keysminor) {
  if ( isset($form['#default_value']) ) {
    return($form['#default_value']);
  }

  $subform = null;
  foreach( $keysminor as $key ) {
    $subform = &$form[$key];
  }

  if ( isset($subform['#default_value']) ) {
    return($subform['#default_value']);
  }

  return("");  
}


function transfer_default_substitutions($form_info,$form) {

  $formtext = $form_info->formtext;
  
  $subsitutions = $form_info->substitutions_keys;
  
  foreach( $subsitutions as $keymajor => $keysminor ) {
    $substval = retrieve_form_defaults($form,$keysminor);
    $formtext = str_replace($keymajor,$substval,$formtext);
  }

  return($formtext);
}



function form_to_be_cached($form_id) {
  $form_info = query_form_description($form_id,$form);
  if ( !isset($form_info) ) return(false);
  return( !($form_info->dynamic) );
}



function store_this_form($form_id,$formtext) {
  $form_info = query_form_description($form_id,$form);
  $form_info->formtext = $formtext;

  module_invoke_all('store_registered_form',$form_id,$form_info);
}





/**
 * Renders a structured form array into themed HTML.
 *
 * @param $form_id
 *   A unique string identifying the form for validation, submission,
 *   theming, and hook_form_alter functions.
 * @param $form
 *   An associative array containing the structure of the form.
 * @return
 *   A string containing the path of the page to display when processing
 *   is complete.
 *
 */
function drupal_render_form($form_id, &$form) {
  global $g_fieldsetCount;
  $g_fieldsetCount = 0;

  $base = null;
  // Don't override #theme if someone already set it.
  if (isset($form['#base'])) {
    $base = $form['#base'];
  }
  
  if (!isset($form['#theme'])) {
    if (theme_get_function($form_id)) {
      $form['#theme'] = $form_id;
    }
    elseif (theme_get_function($base)) {
      $form['#theme'] = $base;
    }
  }
  
  if (isset($form['#pre_render'])) {
    foreach ($form['#pre_render'] as $function) {
      if (function_exists($function)) {
        $function($form_id, $form);
      }
    }
  }
  
   drupal_set_html_head(oat_header($node));

  
  $output = "\n<div id='panelbar'>\n";

  query_form_description($form_id,$form);

  
  $formtext = "";
  if ( !changed_form($form_id,$form) ) {
    $formtext = fetch_prerendered_form($form_id); // As in get it from the DB..
    if ( is_object($formtext) ) { // If this form still needs information loaded into it
      $formtext = transfer_default_substitutions($formtext,$form); // Transfer default values in substitution entries. Return string finally...
    }
  }

  if ( $formtext == "" ) {  // Render it at least once.
    $formtext .= drupal_render($form);
    // Ask this question: Does this form now need to be stored? (Cache the form, put it into the DB.)
    if ( form_to_be_cached($form_id) ) {
      store_this_form($form_id,$formtext);
    }
  }

  $output .= $formtext;
  $output .= "\n</div>\n";

  return $output;
}

In order to make this code work, I made a new file to put in the include directory.
The file is attached, and it requires the following DB definition:

create table {forms} (
 	fid 	integer	 auto_increment
	form_id 	varchar(128),	
	dynamic 	tinyint(3) default 1, 	
	changed 	tinyint(3) default 1,
	formtext 	text,
	substitutions_keys 	varchar(255),
        PRIMARY KEY  (fid) 

An example of use is the following:

// TO and from the DB is required...
////

function copious_rolled_oats_content_registered_forms() {

  static $my_registered_forms = null;

  if ( $my_registered_forms == null ) {
    $formobj = drupal_fetch_form("copious_rolled_oats_content_admin_fields");
    if ( $formobj == null ) {
      $formvals = array();
      $formvals['dynamic'] = false;
      $formvals['changed'] = true;
      $formvals['formtext'] = "";
      $formvals['substitutions_keys'] = null;
      $formobj = (object)($formvals);
    }
    $my_registered_forms = array("copious_rolled_oats_content_admin_fields" => $formobj);
  } 

  return($my_registered_forms);
}



function copious_rolled_oats_content_store_registered_form($form_id,&$form_info) {

  if ( $form_id == "copious_rolled_oats_content_admin_fields" ) {
    $form_info->form_id = $form_id;
    $form_info->changed = false;
    drupal_store_form($form_id,$form_info);
  }
  
  return(null);
}

Oddly, this example works for a form that seems to be very dynamic. But, in truth, the form variability is determined by javascript parameters and not the actual form HTML.
So, as a result, even a highly dynamic form can be rendered just once. Of course, there are many lists, e.g. search results which require new forms every time.