no not at all
loosening the throttle cable nuts will only adjust the tension on the cable, if your cable is tight then it may alter your revs when taking your foot off the pedal because the throttle plate may not close fully instantly.
its always good to have a little bit of slack in the cable
also be careful when tightening the cable nuts above the manifold, the thread is only alloy or plastic or something, so tighten the nuts up hand tight, then just turn a tiny bit extra with a spanner.