`perf report` about 1000x(!) slower in linux 4.15

[Jan-Oliver Kaiser]

Dear perf maintainers,

After upgrading my system to linux 4.15 (from 4.14), `perf report` 
became unusably slow. I estimate a decrease in performance by a factor 
of 100x-1000x. Some 21M perf.data files take about 30 seconds in the 
"Processing events" step.  `git bisect` points to

commit d8a88dd243a170a226aba33e7c53704db2f82aa6 (HEAD, refs/bisect/bad)
Author: Milian Wolff <milian.wolff@xxxxxxxx>
    perf util: Enable handling of inlined frames by default

The slowdown can be worked around with `--no-inline`. If the slowdown is 
expected, I would suggest reverting the default setting here or maybe 
printing a warning if a lot of time is spent on this feature.

Do you need any additional information about my system or the recorded 
data I am looking at?

Thanks,
Janno