Understanding-mathjax-performance.md

-# Dissecting MathJax Performance
+> This is working draft.
 
 This posting gives an overview over the different aspects that affect MathJax performance.
 
@@ -164,7 +164,11 @@ A very basic problem is that the Knuth-Plass bottom-up algorithm we use has to w
 
 We could investigate a fundamentally new approach, letting the browser do the layout for us. The latest CSS modules such as flexbox could enable native rendering speed while offering much improved rendering.
 
+#### Dropping support for legacy browsers
 
+An big questions is how much support for legacy browsers, in particular IE<9, is holding speed back. Browser JavaScript engines changed the way of optimizing javascript execution.
+
+Caveat emptor: this would probably lead to a re-write of much of MathJax.
 
 ## Remarks on speed
 
@@ -195,6 +199,7 @@ Chrome 29: ~1.7sec
 Windows 8 / IE 10: ~2.5sec (virtualbox + Microsoft's free testing VM)
 Windows 7 / IE9: ~3sec (virtualbox + Microsoft's free testing VM)
 Windows 7 / Firefox 22: ~3.8sec (virtualbox + Microsoft's free testing VM)
+Windows 8.1 / IE11: ~3sec (virtualbox + release candidate)
 
 
 A copy of the page with TeX converted to MathML was ~0.5-1 sec slower.
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