The aspects enable a processor to concurrently execute markup language code (e.g., HTML) having embedded scripting language code (e.g., JAVASCRIPT®) during a page load operation by a browser. A markup language parser parses markup language code until embedded scripting language code is encountered. The segment of embedded scripting language code is extracted for execution by a scripting language engine which proceeds concurrently with speculative parsing of the markup language code. Markup language code generated by execution of scripting language code is evaluated to determine if it is well formed, and a partial rollback of the markup language parse and re-parsing of portions of the markup language code is accomplished if not. Concurrent parsing of markup language code and execution of scripting language code, with partial roll back of the parsing process when necessary, continues until all markup language code has been parsed and all scripting language code has been executed.