[HELP] fdo#51239 how to debug "it is slow"

I'd appreciate some help on fdo#51239 which is of the form "doing this
is horribly slow"; how can I profile LibO, i.e. find out where it
spends all its time; if it spends a lot of time in function FOO, can I
also get information on what the call stack looks like "most of the
time"?

Either someone teaches me how to do it (keep in mind the "time spent"
might be in C++ or Java code), or someone just does it and reports
findings in the bug?


Thanks in advance,

-- 
Lionel