Is there a trade-off between competition and competitiveness?

There is a long-standing view that competition is good for efficiency and cost-competitiveness. If this is the case, strict competition enforcement should also be good for international competitiveness. There is also a view that scale lowers cost and makes it easier for firms to compete world-wide, particularly against very large or subsidised firms. If this is true there could be a trade-off between competition enforcement and international competitiveness. Which view is right? Should EU competition enforcement be more tolerant of mergers than it has been in the past?