Performance: imapnio spend most of its time filling stacktraces

[chibenwa]

Description

An analysis of imapnio with a profiler showed most of its time is spent filling stack traces due to integer parsing.

The underlying IMAPResponse from javax.mail does an attempt to parse untagged responses under the format * NUMBER KEYWORD exemple * 36 EXISTS.

However some commands like LIST

Expected Behavior

Avoid filling this stacktrace.

Actual Behavior

Fills the stacktrace and spends a lot of time doing so (40% of CPU time dedicated to imapnio)

Possible Fix

It looks like overriding this behaviour in IMAPResponse not to be feasible (init method doing such a check is private)

Context

I am using imapnio to write an IMAP benchmarking tool: https://github.com/linagora/gatling-imap/ . As such, in order not to impact performance measurement low latencies are paramount on the injection side.