I realised that when I extrude sketches, NX only uses one CPU core. When I extrude more complicated sketches, it takes quite a while.
Is there anythin I can do?
SET UGII_SMP_ENABLE is set to 1.
Do a search on this site, there are explanations,
See the link, great post by John Baker.
There's also this similar thread: NX using only one core while loading assembly
every parametric CADs are slowly with complicated sketches. Start modelling with 'best practice'. One of them is 'use simple sketch'.