It should be possible to bump allocation interval sufficiently so that you get right frequency of profile dumps.

But for your use-case I'd consider growth samples. Or capturing heap sample at the peak (you'd have to detect it manually though). See MallocExtension::GetHeapSample and MallocExtension::GetHeapGrowthStacks. You then dump those strings to file and feed it to pprof. And extra trick is to compare good versus bad runs with --base arg.