Getting plan details isn’t free. The amount of impact depends on what the query is doing, but there’s a stiff overhead to collecting actual execution plans and to watching live query statistics.
These tools are great for reproing problems and testing outside of production, but don’t time query performance while you’re using them– you’ll get too much skew.
Live Query Statistics is one additional tool, but won’t replace actual execution plans. At its best, it will make you think more about what’s going on with the system, whether row counts are what you’re expecting, and take account of which operators stream data through without blocking (such as nested loop joins) versus those which require all the data before continuing (sorts).