Performance regression for Button creation benchmark

a7d9818dd414565cdcc4f4c9415f67735d146c68:

mitch@mitch-ubuntu:~/dev/qmlbench-qt5-dev-release$ QSG_RENDER_LOOP=windows ./src/qmlbench --shell frame-count ~/dev/qmlbench/benchmarks/auto/creation/controls/delegates_buttoncontrol2.qml 
ID:          
OS:          Ubuntu 16.04.2 LTS
QPA:         xcb
GL_VENDOR:   Intel Open Source Technology Center
GL_RENDERER: Mesa DRI Intel(R) Haswell Desktop 
GL_VERSION:  3.0 Mesa 12.0.6
SUB: running: /home/mitch/dev/qmlbench/benchmarks/auto/creation/controls/delegates_buttoncontrol2.qml
SUB:     120 frames
SUB:     119 frames
SUB:     119 frames
SUB:     117 frames
SUB:     118 frames
SUB:     Average: 118.6  frames; using  samples; MedianAll=119; StdDev=1.14018, CoV=0.00961362
SUB: All done...
mitch@mitch-ubuntu:~/dev/qmlbench-qt5-dev-release$ 

b0d2e6d:

mitch@mitch-ubuntu:~/dev/qmlbench-qt5-dev-release$ QSG_RENDER_LOOP=windows ./src/qmlbench --shell frame-count ~/dev/qmlbench/benchmarks/auto/creation/controls/delegates_buttoncontrol2.qml 
ID:          
OS:          Ubuntu 16.04.2 LTS
QPA:         xcb
GL_VENDOR:   Intel Open Source Technology Center
GL_RENDERER: Mesa DRI Intel(R) Haswell Desktop 
GL_VERSION:  3.0 Mesa 12.0.6
SUB: running: /home/mitch/dev/qmlbench/benchmarks/auto/creation/controls/delegates_buttoncontrol2.qml
SUB:     167 frames
SUB:     168 frames
SUB:     169 frames
SUB:     169 frames
SUB:     168 frames
SUB:     Average: 168.2  frames; using  samples; MedianAll=168; StdDev=0.83666, CoV=0.0049742
SUB: All done...
mitch@mitch-ubuntu:~/dev/qmlbench-qt5-dev-release$ 

4600236:

mitch@mitch-ubuntu:~/dev/qmlbench-qt5-dev-release$ QSG_RENDER_LOOP=windows ./src/qmlbench --shell frame-count ~/dev/qmlbench/benchmarks/auto/creation/controls/delegates_buttoncontrol2.qml 
ID:          
OS:          Ubuntu 16.04.2 LTS
QPA:         xcb
GL_VENDOR:   Intel Open Source Technology Center
GL_RENDERER: Mesa DRI Intel(R) Haswell Desktop 
GL_VERSION:  3.0 Mesa 12.0.6
SUB: running: /home/mitch/dev/qmlbench/benchmarks/auto/creation/controls/delegates_buttoncontrol2.qml
SUB:     168 frames
SUB:     169 frames
SUB:     170 frames
SUB:     168 frames
SUB:     167 frames
SUB:     Average: 168.4  frames; using  samples; MedianAll=168; StdDev=1.14018, CoV=0.00677064
SUB: All done...
mitch@mitch-ubuntu:~/dev/qmlbench-qt5-dev-release$