Upon each invocation of the PHP application, Smarty tests to see if the
current template has changed (different time stamp) since the last time
it was compiled. If it has changed, it recompiles that template. If the
template has not been compiled, it will compile regardless of this
setting. By default this variable is set to true. Once an application is
put into production (templates won't be changing), the compile_check
step is no longer needed. Be sure to set $compile_check to "false" for
maximal performance. Note that if you change this to "false" and a
template file is changed, you will *not* see the change since the
template will not get recompiled. If caching is enabled and
compile_check is enabled, then the cache files will get regenerated if
an involved template file or config file was updated. See $force_compile or clear_compiled_tpl.