[Mediawiki-l] $wgAllowSlowParserFunctions... not very reassuring

[Wikimini]

Hi,

I've just seen the possibility to display the number of pages in a
given namsepace with the magic word {{PAGESINNAMESPACE}}. But this
requires $wgAllowSlowParserFunctions to be enabled.

This name is not very reassuring (as far as I understand it with my
limited english). Is it OK to enable this parameter or would that be a
resource heavy bad idea ?

Thanks for any advice.

Laurent