Display elapsed time per task if enabled via
ProgressMonitor#showDuration or if system property or environment
variable GIT_TRACE_PERFORMANCE is set to "true". If both the system
property and the environment variable are set the system property takes
precedence.
E.g. using jgit CLI:
$ GIT_TRACE_PERFORMANCE=true jgit clone https://foo.bar/foobar
Cloning into 'foobar'...
remote: Counting objects: 1 [0.002s]
remote: Finding sources: 100% (15531/15531) [0.006s]
Receiving objects: 100% (169737/169737) [13.045s]
Resolving deltas: 100% (67579/67579) [1.842s]
Change-Id: I4d624e7858b286aeddbe7d4e557589986d73659e
2d0b908048