Itunes 12.3.0.44 Unusable Pre/Post El Capitan

Macbook Pro now running El Capitan, iPhone 5s with latest 9.0.2 update.

iTunes very slow to open, lots of "beachball" action, mostly unresponsive.

Takes a very long time to even recognize phone.

Once iPhone connected, will not sync; seems to start but hangs up.

I've tried ejecting iPhone and restarting to no avail.

Cleared everything from My Music Library and tried a clean sync but, when I select "On My Device - Music",

window shows as if still trying to accomplish an older sync request that never finished/froze up.

Any ideas?