Optimize string splitting by using Splitter class

Instead of performing costli String.split() operation, instantiate a
shared Splitter and use it to split the string. Requires slight
alterations to logic, but those are rather obvious.

Change-Id: Icec3c4588e062373c090b3479635a93428f278f1
Signed-off-by: Robert Varga <robert.varga@pantheon.sk>