>>421
<< の測定前にGCしたら変わったりして

N=1000000
t0=Time::times; N.times{str='efgh';str2='abcd';str=str+str2}; t1=Time::times
u,s=t1.utime-t0.utime,t1.stime-t0.stime
printf("%-2s user %7.4f, system %7.4f, total %7.4f\n", "+", u,s,u+s)
GC.start
t0=Time::times; N.times{str='efgh';str2='abcd';str<<str2}; t1=Time::times
u,s=t1.utime-t0.utime,t1.stime-t0.stime
printf("%-2s user %7.4f, system %7.4f, total %7.4f\n", "<<", u,s,u+s)