Recognising SLs seems slow

[ssiccha]

@fingolfin and @danielrademacher mentioned this during a jitsi call:
The call RecognizeGroup(SL(40,3)); takes pretty long. Once one knows the name of the group, doing the constructive recognition by RECOG.FindStdGens_SL(SL(40,3),GF(3)); is quick.

[fingolfin]

Even finding the name is reasonably fast. Next thing to test would be to see how slow/fast calling FindHomMethodsProjective.ClassicalNatural is (which calls RECOG.FindStdGens_SL among other things). And then of course one could run the profiler to see where else we spend/waste time.

[danielrademacher]

I have looked into this.

The function 'FindHomMethodsProjective.ClassicalNatural' was pretty fast. I summarise the lines which used a lot of time:
250ms:
rifac := RecogniseGeneric(
Group(List(GeneratorsOfGroup(H), x->ImageElm(Homom(ri),x))),
methodsforfactor(ri), depth, forfactor(ri) );

200ms:
Setpregensfac( ri, CalcNiceGens(rifac,ri!.gensHmem) );

1850ms:
succ := CallFuncList(methgensN.method,
Concatenation([ri],methgensN.args));

These three lines are basically the bottlenecks for the call 'RecognizeGroup(SL(40,3));'