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== The cost/benefit of UTF8 ==

Question: If we moved from our current UCS2/UTF16 storage for nsAString to UTF8, what would the impact be on memory usage?

Procedure: 

Instrument [http://mxr.mozilla.org/mozilla/source/xpcom/string/public/nsStringBuffer.h nsStringBuffer] with a large linked-list (with locking and all that good stuff). Run the instrumented browser and collect data about all nsStringBuffers which hold PRUnichar data:

* What is the size of the buffer
* What would the size of the buffer be in UTF8?
* Is the buffer pure-ASCII?

== Conversion counts ==

Question: how much do we currently convert between UTF8 and UTF16?

Procedure:
Instrument the number of calls to [http://mxr.mozilla.org/mozilla/source/xpcom/string/public/nsUTF8Utils.h#459 ConvertUTF8toUTF16] and [http://mxr.mozilla.org/mozilla/source/xpcom/string/public/nsUTF8Utils.h#611 ConvertUTF16toUTF8].

Bonus points: group and identify common callstacks

== Autostring value ==

* Dynamic analysis: autostring buffer-copy counts (are autostrings worthwhile)? 

Procedure: todo [dmandelin] Does this mean (a) the fraction of nsAutoStrings that grow big enough to get moved to the heap, (b) the fraction of nsAutoStrings that end up being used to initialize a standard heap string, or both?