music file stutters -- linux 1.5.2

Good morning all, as the subject states, playback stutters at random times.
This is on Fedora 21, transcoding is off.
This is new behavior with 1.5.2, the 1.4.1.2 install sent the same files to the same device [ a Pioneer N-50 ] without a glitch. There are a fairly large number of files, all .flac and most in standard rez, but that was also true with 1.4.1.2, and things were snappier...
Please let me know if there is any specific test that could be done and that would be revealing... the database seems to work harder than it used to and response time at the renderer end of things seems sluggish... compared to the previous rev while browsing and selecting tracks to play, I mean.
The derby.log file is below, just in case that is a clue...
thanks and any help appreciated,
rikm
====
Sun Apr 26 06:40:50 MST 2015:
Booting Derby version The Apache Software Foundation - Apache Derby - 10.11.1.1 - (1616546): instance a816c00e-014c-f5f5-819c-ffff904ea03a
on database directory /opt/serviio/library/db with class loader sun.misc.Launcher$AppClassLoader@4d7e1886
Loaded from file:/opt/serviio/lib/derby.jar
java.vendor=Oracle Corporation
java.runtime.version=1.8.0_45-debug-b13
user.dir=/
os.name=Linux
os.arch=amd64
os.version=3.19.4-200.fc21.x86_64
derby.system.home=/opt/serviio/library
derby.stream.error.file=../log/derby.log
Database Class Loader started - derby.database.classpath=''
Derby could not obtain the locks needed to release the unused, preallocated values for the sequence 'SYS'.'U2c864112X014cXf5f5X819cXffff904ea03a'. As a result,
Derby could not obtain the locks needed to release the unused, preallocated values for the sequence 'SYS'.'U2c864112X014cXf5f5X819cXffff904ea03a'. As a result,
Derby could not obtain the locks needed to release the unused, preallocated values for the sequence 'SYS'.'U2c864112X014cXf5f5X819cXffff904ea03a'. As a result,
====
This is on Fedora 21, transcoding is off.
This is new behavior with 1.5.2, the 1.4.1.2 install sent the same files to the same device [ a Pioneer N-50 ] without a glitch. There are a fairly large number of files, all .flac and most in standard rez, but that was also true with 1.4.1.2, and things were snappier...
Please let me know if there is any specific test that could be done and that would be revealing... the database seems to work harder than it used to and response time at the renderer end of things seems sluggish... compared to the previous rev while browsing and selecting tracks to play, I mean.
The derby.log file is below, just in case that is a clue...
thanks and any help appreciated,
rikm
====
Sun Apr 26 06:40:50 MST 2015:
Booting Derby version The Apache Software Foundation - Apache Derby - 10.11.1.1 - (1616546): instance a816c00e-014c-f5f5-819c-ffff904ea03a
on database directory /opt/serviio/library/db with class loader sun.misc.Launcher$AppClassLoader@4d7e1886
Loaded from file:/opt/serviio/lib/derby.jar
java.vendor=Oracle Corporation
java.runtime.version=1.8.0_45-debug-b13
user.dir=/
os.name=Linux
os.arch=amd64
os.version=3.19.4-200.fc21.x86_64
derby.system.home=/opt/serviio/library
derby.stream.error.file=../log/derby.log
Database Class Loader started - derby.database.classpath=''
Derby could not obtain the locks needed to release the unused, preallocated values for the sequence 'SYS'.'U2c864112X014cXf5f5X819cXffff904ea03a'. As a result,
Derby could not obtain the locks needed to release the unused, preallocated values for the sequence 'SYS'.'U2c864112X014cXf5f5X819cXffff904ea03a'. As a result,
Derby could not obtain the locks needed to release the unused, preallocated values for the sequence 'SYS'.'U2c864112X014cXf5f5X819cXffff904ea03a'. As a result,
====