Infer does bottom-up analysis: it starts at the bottom of the call graph and analyzes each procedure once independently of its callers. Analyzing the procedure produces a concise summary of its behavior that can be used in each calling procedure. This means that the cost of the analysis is roughly linear in the number of nodes in the call graph, which is not true for a lot of other interprocedural analysis techniques.

It's true that it a procedure changes that you may have to re-analyze all dependent procedures (and calling procedures!) in the worst case. However, in the bottom-up scheme you only need to re-analyze a procedure when the code change produces a change in the computed summary, and in practice summaries are frequently quite stable.