VLC and SMPlayer become sluggish as they're used

[Fedora]

Greetings,

I'm using KXStudio (everything upgraded) and after playing a few video files (karaoke tracks), VLX and SMPlayer become sluggish to respond and eventually stop responding.

If I start the media player directly or via the command line, I don't see the sluggishness appear, but I don't see any errors either. The CPU load never goes over about 30%. I just can't figure out how to diagnose the issue. Any suggestions on where to look for useful error messages?

The system is an Intel 4300 (dual core at 1.8GHz)
4GB of RAM
240GB SSD, 2 80GB HDD's
Nvidia GTS 250
Ensoniq PCI audio card

I'm using Non Session Mgr to start:
Non Mixer, Carla and JackPatch
NSM Proxy starts - QJackCTL, VLC, Catia, and Darksnow (for streaming the audio output)

Thanks for any pointers!

JMJ

[Fedora]

I just remembered strace (https://en.wikipedia.org/wiki/Strace), so I'll try using that and see what happens.

Perhaps BitMeter (http://devel.tlrmx.org/audio/bitmeter/) will provide some useful info.

What other diagnostic tools might be of use?