Effect of Profile-Guided Optimization

I built RecoverSegmentBenchmark with -fprofile-generate, ran it, rebuilt with -fprofile-use, then reran it. This brings about a 5% improvement in time for the benchmark for smaller object sizes and doesn't hurt times for larger object sizes.

object size	64	128	256	512	1024	2048	8192
normal	1535.88	1104.6	830.9	661.58	547.98	487.12	422.5
PGO	1444.171875	1044.609375	780.734375	626.46875	551.875	480.515625	420.109375
% improvement	5.97%	5.43%	6.04%	5.31%	-0.71%	1.36%	0.57%