Instruments 27 introduces Run Comparisons — a new mode that directly diffs two profiling traces side-by-side in a single document to calculate exact performance deltas — alongside the new Top Functions analysis mode that merges scattered call-tree nodes by self-weight to instantly surface the costliest functions regardless of call hierarchy.
• Run Comparisons eliminates manual window juggling: load a baseline trace and an optimized trace together, and Instruments cross-references every sample to show you the exact delta per function — making it fast to verify that a fix actually helped.
• Top Functions mode solves a long-standing flame graph blind spot: runtime helpers and utilities called from many sites are shown as one merged block sorted by self-weight, so you immediately see the true most-expensive function rather than fragmented slices.
• OSSignpost / Points-of-Interest integration lets you annotate specific user-facing workflows (like lasso selection) and filter the entire trace to that window, dramatically narrowing the search space before you even open the call tree.