Krunner crashed when I typed "konsole" and pressed Enter. There was high IO as I was typing, and krunner was not being able to keep up with the search for items (the list below the typing field was empty). This may be the cause of the problem.

Thread 1 (Thread 0x7ff374b8e7c0 (LWP 1691)):
[KCrash Handler]
#6  0x00007ff3506018db in  () at /usr/lib/x86_64-linux-gnu/qt5/plugins/sqldrivers/libqsqlite.so
#7  0x00007ff346bfeeb5 in Firefox::teardown() (this=0x7ff3140036d0) at ../../../runners/bookmarks/browsers/firefox.cpp:114
#8  0x00007ff371eba9c9 in QMetaObject::activate(QObject*, int, int, void**) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#9  0x00007ff350eadd7d in Plasma::RunnerManager::matchSessionComplete() () at /usr/lib/x86_64-linux-gnu/libKF5Runner.so.5
#10 0x00007ff3510c7e12 in Milou::SourcesModel::clear() () at /usr/lib/x86_64-linux-gnu/libmilou.so.5
#11 0x00007ff3510c7fd8 in Milou::SourcesModel::setQueryString(QString const&) () at /usr/lib/x86_64-linux-gnu/libmilou.so.5
#12 0x00007ff3510cd3fa in Milou::SourcesModel::qt_metacall(QMetaObject::Call, int, void**) () at /usr/lib/x86_64-linux-gnu/libmilou.so.5
#13 0x00007ff372d50fb1 in QQmlVMEMetaObject::metaCall(QMetaObject::Call, int, void**) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#14 0x00007ff372d6e1fa in QQmlPropertyPrivate::writeBinding(QObject*, QQmlPropertyData const&, QQmlContextData*, QQmlJavaScriptExpression*, QV4::ValueRef, bool, QFlags<QQmlPropertyPrivate::WriteFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#15 0x00007ff372de251c in QQmlBinding::update(QFlags<QQmlPropertyPrivate::WriteFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#16 0x00007ff372de2c7e in QQmlBinding::expressionChanged(QQmlJavaScriptExpression*) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#17 0x00007ff372dbc497 in QQmlNotifier::emitNotify(QQmlNotifierEndpoint*, void**) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#18 0x00007ff372d5910c in QQmlData::signalEmitted(QAbstractDeclarativeData*, QObject*, int, void**) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#19 0x00007ff371eba141 in QMetaObject::activate(QObject*, int, int, void**) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#20 0x00007ff372d514d0 in QQmlVMEMetaObject::metaCall(QMetaObject::Call, int, void**) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#21 0x00007ff372d3aa42 in QV4::QObjectWrapper::setProperty(QObject*, QV4::ExecutionContext*, QQmlPropertyData*, QV4::ValueRef) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#22 0x00007ff372d3b056 in QV4::QObjectWrapper::setQmlProperty(QV4::ExecutionContext*, QQmlContextData*, QObject*, QV4::String*, QV4::QObjectWrapper::RevisionMode, QV4::ValueRef) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#23 0x00007ff372d3b18d in QV4::QObjectWrapper::put(QV4::Managed*, QV4::String*, QV4::ValueRef) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#24 0x00007ff372d420ed in QV4::Runtime::setProperty(QV4::ExecutionContext*, QV4::ValueRef, QV4::String*, QV4::ValueRef) () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5


Reproducible: Didn't try

Steps to Reproduce:
1. [probably] Make sure the system was under a heavy load previously. For instance, compile a large project so that some memory is swapped in the process.
2. When the system is idle again, press Alt+F2 so that krunner appears. Type in a program name and press enter.


Actual Results:  
Krunner appeared sluggish and crashed when I pressed Enter.

Expected Results:  
Krunner should not crash.

Kubuntu 15.04, x86_64, Plasma 5.3 installed from Kubuntu backports.