I benchmarked it:

The string: "now is the time for all good monks to come to the aid of their perl". The results:

Benchmark: timing 5000000 iterations of /.*perl/, /^.*perl/, /perl/...
  /.*perl/: 43 secs (41.48 usr  0.00 sys = 41.48 cpu)
 /^.*perl/: 38 secs (36.20 usr  0.00 sys = 36.20 cpu)
    /perl/: 29 secs (28.96 usr  0.00 sys = 28.96 cpu)
[download]

So yah, a standalone /match/ is going to be a bit faster.