[GAP Forum] speed of Core vs IsNormal

[William DeMeo]

I apologize if this is a dumb question, but I'm trying to speed up a
program that is searching for certain groups. In the examples I'm
looking for, I have a subgroup H of a group G and I need to test
(among other things) whether it is core-free.  I was wondering if
someone could tell me whether it would speed things up greatly if I
first tested to see if the subgroup itself is normal.

So, I'm wondering if I should simply do:

e:=Group([Identity(G)]);

if Core(G,H)=e then

    # test other search criteria
    ...

Or would I do better to test for normality of the subgroup first:

if IsNormal(G,H) and H<>e then

    # do nothing

elif Core(G,H)=e then

    # test other search criteria


Would the latter speed things up greatly?  Is computing Core much more
expensive than first testing IsNormal?

Thanks and, again, I apologize if this is dumb.

-William