End-to-end profiling with Oracle APEX?

With my current employer, our primary development platform is Oracle Database SE (11g/12c) and APEX (4.2 and 5.0).

I understand that mostly, when I encounter a performance problem in an APEX application, it's very likely to be developer-produced SQL and PL/SQL code. And that, I can usually handle without too much difficulty.

However, occasionally, I get a report like "Screen 207 is really slow on application xyz".

In some cases, though this particular APEX screen is slow in terms of ed-user response time, I'm not seeing any obvious slow SQL or PL/SQL on the database. And, I'm not *at all* an APEX developer. I really have very little knowledge and experience of APEX.

So, I'm looking for ideas in terms of end-to-end profiling of APEX processes. If user clicks 'search' how much time is spent in browser? How much in DB? How much in rendering output?

Is there a way to get a more complete profile picture of APEX end-user response time?

Any thoughts or suggestions? APEX is a big black box to me, at the moment.

Thanks,