beagrep performance tuning on MacbookAir+Linux

beagrep has been slow on my MacbookAir with Linux installation. Where it takes 0.23 second to beagrep -e readlink on my Optiplex 960, it took about 1 second on my MBA.

Finally it turns out to be the cpu clock is locked at 800MHz on MBA. See Linux on a MacBook Air 2012 for how to fix this.

With this change, bare grep is still not as fast as it is on Optiplex 960: where Optiplex 960 takes only 3.5s, MacbookAir is taking 40 seconds. And same with beagrep: where Optiplex 960 takes 0.23s to beagrep Android, MacbookAir is taking 0.38s.