Well So far, not much..!
Compatibility issue with office 2003 fixed.
Starts much faster as described below on my PC Specs here:

 

Specs as follow

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Windows XP Professional Service Pack 3
Intel(R) Pentium(R) 4 CPU 3.20GHz
Memory: 992MB RAM
Chipset: SiS 661FX
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Start times:

First start of the program, right after install, no brushes, etc added.
01 Min 02 Sec
Second start, right after the first (Without restart).
10 Sec

After Restart :

24 Sec
Edit image, right after the restart (Without restart).
10 sec

Note

I may have to note that I have a tweak that clears the ram form .dll files after closing the program, maybe it’s part of the thing, you can find it in this thread, works even on Windows 7 starter, and may work on others two.
P.S: I read somewhere on the web that brushes add 05 Sec to the startup pf the program.