[Qt-interest] Text Handling speed on Mac (ATSUI, Core Text, Harfbuzz?)

[Joshua Grauman]

Hello all,

I've just gotten my first Mac to port my Qt application over to mac os. I 
was able to port it over, but it is running quite a bit slower than under 
Linux (and Windows). Last I heard Qt was using ATSUI for text rendering on 
Mac, but Harfbuzz on Linux and Windows and since my application is heavily 
text based I'm wondering if this is causing the slowdown. So my questions:

1) Can someone confirm that Qt is still using ATSUI for Mac?

2) Is there any plans to move to Core Text or even Harfbuzz on Mac?

3) Is there any reason I couldn't make a couple minor changes to the Qt 
code and use Harfbuzz on Mac (I don't need any system fonts, I supply all 
my own which are all TrueType/OpenType).

4) Are there any other compiling gotchas for Mac I should be aware of that 
would effect application speed? I downloaded the Qt4.6 binary package for 
Cocoa and ran qmake with "-spec macx-g++". I'm assuming I'm compiling 
64-bit native binaries, but I'm completely new to Mac so I don't have any 
idea. *Any hints* are appreciated.

Thanks!

Josh