Perhaps you set shape-rendering property for root svg element.
You should set shape-rendering property for each shape elements, like this.
<?xml version="1.0" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<rect x="10" y="10" width="150" height="20" shape-rendering="crispEdges"
fill="none" stroke="black"/>
<path d="M80,30l100,100" shape-rendering="optimizeQuality"
stroke="black" stroke-width="5"/>
</svg>